diff --git a/.gitmodules b/.gitmodules
index bffa3e75..9f45b9a5 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
-[submodule "diem"]
+[submodule "diem_testnet_tag"]
 	path = diem
 	url = https://github.com/diem/diem.git
diff --git a/diem b/diem
index 3916c548..1a6910c2 160000
--- a/diem
+++ b/diem
@@ -1 +1 @@
-Subproject commit 3916c548380111f241d9ffbf7eecc09929bd2f4a
+Subproject commit 1a6910c2fad633a09a38f2774596fa989ffcfed0
diff --git a/requirements.txt b/requirements.txt
index 84d1244c..e713e87d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,10 +4,10 @@ numpy==1.18
 protobuf==3.12.4
 pytest==6.2.1
 pytest-asyncio==0.14.0
-click==7.1
+click==8.1.3
 aiohttp==3.7.4.post0
 pylama
-black
+black==22.10.0
 pyre-check
 pytest-cov
 mypy-protobuf
diff --git a/src/diem/identifier/bech32.py b/src/diem/identifier/bech32.py
index 01d82f07..c3de41d6 100644
--- a/src/diem/identifier/bech32.py
+++ b/src/diem/identifier/bech32.py
@@ -23,7 +23,7 @@
 
 
 class Bech32Error(Exception):
-    """ Represents an error when creating a Diem address. """
+    """Represents an error when creating a Diem address."""
 
     pass
 
diff --git a/src/diem/jsonrpc/async_client.py b/src/diem/jsonrpc/async_client.py
index e4804717..97186904 100644
--- a/src/diem/jsonrpc/async_client.py
+++ b/src/diem/jsonrpc/async_client.py
@@ -564,6 +564,7 @@ async def execute_without_retry(
             "method": method,
             "params": params or [],
         }
+        json = {}
         try:
             json = await self._rs.send_request(self, request, ignore_stale_response or False)
             if "error" in json:
diff --git a/src/diem/jsonrpc/client.py b/src/diem/jsonrpc/client.py
index 455078c7..20babb3a 100644
--- a/src/diem/jsonrpc/client.py
+++ b/src/diem/jsonrpc/client.py
@@ -108,12 +108,7 @@ class RequestWithBackups(RequestStrategy):
     ```
     """
 
-    def __init__(
-        self,
-        backups: typing.List[str],
-        executor: ThreadPoolExecutor,
-        fallback: bool = False,
-    ) -> None:
+    def __init__(self, backups: typing.List[str], executor: ThreadPoolExecutor, fallback: bool = False) -> None:
         self._backups = backups
         self._executor = executor
         self._fallback = fallback
@@ -268,16 +263,9 @@ def update_last_known_state(self, chain_id: int, version: int, timestamp_usecs:
             if curr.timestamp_usecs > timestamp_usecs:
                 raise StaleResponseError(f"last known timestamp_usecs {curr.timestamp_usecs} > {timestamp_usecs}")
 
-            self._last_known_server_state = State(
-                chain_id=chain_id,
-                version=version,
-                timestamp_usecs=timestamp_usecs,
-            )
+            self._last_known_server_state = State(chain_id=chain_id, version=version, timestamp_usecs=timestamp_usecs)
 
-    def get_metadata(
-        self,
-        version: typing.Optional[int] = None,
-    ) -> rpc.Metadata:
+    def get_metadata(self, version: typing.Optional[int] = None) -> rpc.Metadata:
         """get block metadata
 
         See [JSON-RPC API Doc](https://github.com/diem/diem/blob/master/json-rpc/docs/method_get_metadata.md)
@@ -342,10 +330,7 @@ def get_account_transactions(
         return self.execute("get_account_transactions", params, _parse_list(lambda: rpc.Transaction()))
 
     def get_transactions(
-        self,
-        start_version: int,
-        limit: int,
-        include_events: typing.Optional[bool] = None,
+        self, start_version: int, limit: int, include_events: typing.Optional[bool] = None
     ) -> typing.List[rpc.Transaction]:
         """get transactions
 
@@ -403,10 +388,7 @@ def support_diem_id(self) -> bool:
         tc_account = self.must_get_account(TREASURY_ADDRESS)
         return bool(tc_account.role.vasp_domain_events_key)
 
-    def submit(
-        self,
-        txn: typing.Union[diem_types.SignedTransaction, str],
-    ) -> None:
+    def submit(self, txn: typing.Union[diem_types.SignedTransaction, str]) -> None:
         """submit signed transaction
 
         See [JSON-RPC API Doc](https://github.com/diem/diem/blob/master/json-rpc/docs/method_submit.md)
@@ -564,12 +546,9 @@ def execute_without_retry(
         Raises NetworkError if send http request failed, or received server response status is not 200.
         """
 
-        request = {
-            "jsonrpc": "2.0",
-            "id": 1,
-            "method": method,
-            "params": params or [],
-        }
+        request = {"jsonrpc": "2.0", "id": 1, "method": method, "params": params or []}
+
+        json = {}
         try:
             json = self._rs.send_request(self, request, ignore_stale_response or False)
             if "error" in json:
@@ -588,10 +567,7 @@ def execute_without_retry(
             raise InvalidServerResponse(f"Parse result failed: {e}, response: {json}")
 
     def _send_http_request(
-        self,
-        url: str,
-        request: typing.Dict[str, typing.Any],
-        ignore_stale_response: bool,
+        self, url: str, request: typing.Dict[str, typing.Any], ignore_stale_response: bool
     ) -> typing.Dict[str, typing.Any]:
         self._logger.debug("http request body: %s", request)
         response = self._session.post(url, json=request, timeout=self._timeout)
@@ -605,9 +581,7 @@ def _send_http_request(
         # check stable response before check jsonrpc error
         try:
             self.update_last_known_state(
-                json.get("diem_chain_id"),
-                json.get("diem_ledger_version"),
-                json.get("diem_ledger_timestampusec"),
+                json.get("diem_chain_id"), json.get("diem_ledger_version"), json.get("diem_ledger_timestampusec")
             )
         except StaleResponseError as e:
             if not ignore_stale_response:
diff --git a/src/diem/offchain/command.py b/src/diem/offchain/command.py
index 5ed4d650..6dc7377c 100644
--- a/src/diem/offchain/command.py
+++ b/src/diem/offchain/command.py
@@ -9,7 +9,7 @@
 
 
 class Command(ABC):
-    """Command defines common interface for all commands """
+    """Command defines common interface for all commands"""
 
     @abstractmethod
     def id(self) -> str:
diff --git a/src/diem/offchain/types/__init__.py b/src/diem/offchain/types/__init__.py
index 60d7b3b2..851c8f51 100644
--- a/src/diem/offchain/types/__init__.py
+++ b/src/diem/offchain/types/__init__.py
@@ -124,7 +124,7 @@ def _field_value_from_dict(field: dataclasses.Field, obj: typing.Any, field_path
     full_name = _join_field_path(field_path, field.name)
     field_type = field.type
     args = field.type.__args__ if hasattr(field.type, "__args__") else []
-    is_optional = len(args) == 2 and isinstance(None, args[1])  # pyre-ignore
+    is_optional = len(args) == 2 and isinstance(None, args[1])
     if is_optional:
         field_type = args[0]
     val = obj.get(field.name)
@@ -166,14 +166,9 @@ def new_payment_object(
     return PaymentObject(
         reference_id=reference_id or str(uuid.uuid4()),
         sender=PaymentActorObject(
-            address=sender_account_id,
-            kyc_data=sender_kyc_data,
-            status=StatusObject(status=Status.needs_kyc_data),
-        ),
-        receiver=PaymentActorObject(
-            address=receiver_account_id,
-            status=StatusObject(status=Status.none),
+            address=sender_account_id, kyc_data=sender_kyc_data, status=StatusObject(status=Status.needs_kyc_data)
         ),
+        receiver=PaymentActorObject(address=receiver_account_id, status=StatusObject(status=Status.none)),
         action=PaymentActionObject(amount=amount, currency=currency),
         description=description,
         original_payment_reference_id=original_payment_reference_id,
@@ -196,10 +191,7 @@ def replace_payment_actor(
         changes["additional_kyc_data"] = additional_kyc_data
     if status or abort_code or abort_message:
         changes["status"] = replace_payment_status(
-            actor.status,
-            status=status,
-            abort_code=abort_code,
-            abort_message=abort_message,
+            actor.status, status=status, abort_code=abort_code, abort_message=abort_message
         )
     if metadata:
         if not isinstance(metadata, list):
@@ -224,19 +216,11 @@ def replace_payment_status(
     return dataclasses.replace(status_obj, **changes)
 
 
-def new_payment_request(
-    payment: PaymentObject,
-    cid: typing.Optional[str] = None,
-) -> CommandRequestObject:
+def new_payment_request(payment: PaymentObject, cid: typing.Optional[str] = None) -> CommandRequestObject:
     return CommandRequestObject(
         cid=cid or str(uuid.uuid4()),
         command_type=CommandType.PaymentCommand,
-        command=to_dict(
-            PaymentCommandObject(
-                _ObjectType=CommandType.PaymentCommand,
-                payment=payment,
-            )
-        ),
+        command=to_dict(PaymentCommandObject(_ObjectType=CommandType.PaymentCommand, payment=payment)),
     )
 
 
@@ -254,17 +238,11 @@ def reply_request(
 
 
 def individual_kyc_data(**kwargs) -> KycDataObject:  # pyre-ignore
-    return KycDataObject(
-        type=KycDataObjectType.individual,
-        **kwargs,
-    )
+    return KycDataObject(type=KycDataObjectType.individual, **kwargs)
 
 
 def entity_kyc_data(**kwargs) -> KycDataObject:  # pyre-ignore
-    return KycDataObject(
-        type=KycDataObjectType.entity,
-        **kwargs,
-    )
+    return KycDataObject(type=KycDataObjectType.entity, **kwargs)
 
 
 def validate_write_once_fields(path: str, new: typing.Any, prior: typing.Any) -> None:  # pyre-ignore
diff --git a/src/diem/offchain/types/command_types.py b/src/diem/offchain/types/command_types.py
index 38442301..de867225 100644
--- a/src/diem/offchain/types/command_types.py
+++ b/src/diem/offchain/types/command_types.py
@@ -98,7 +98,7 @@ class OffChainErrorType:
 
 
 class OffChainCommandResponseResultType:
-    """ Type of result in a CommandResponseObject"""
+    """Type of result in a CommandResponseObject"""
 
     ReferenceIDCommandResponse = "ReferenceIDCommandResponse"
 
diff --git a/src/diem/testing/cli.py b/src/diem/testing/cli.py
index c5408aa4..8c7f0710 100644
--- a/src/diem/testing/cli.py
+++ b/src/diem/testing/cli.py
@@ -14,7 +14,7 @@
 
 
 log_format: str = "%(name)s [%(asctime)s] %(levelname)s: %(message)s"
-click.option = functools.partial(click.option, show_default=True)  # pyre-ignore
+click.option = functools.partial(click.option, show_default=True)
 
 
 def coro(f):  # pyre-ignore
@@ -187,13 +187,7 @@ async def start_server(
     help="Before start test, the target wallet application host port should be ready for connection. This is wait timeout (seconds) for the port ready.",
     type=int,
 )
-@click.option(
-    "--include-offchain-v2",
-    type=bool,
-    is_flag=True,
-    default=False,
-    help="Include offchain v2 test suites",
-)
+@click.option("--include-offchain-v2", type=bool, is_flag=True, default=False, help="Include offchain v2 test suites")
 @click.help_option("-h", "--help")
 def test(
     target: str,
diff --git a/src/diem/testing/miniwallet/app/app.py b/src/diem/testing/miniwallet/app/app.py
index a0270726..37c9e427 100644
--- a/src/diem/testing/miniwallet/app/app.py
+++ b/src/diem/testing/miniwallet/app/app.py
@@ -149,7 +149,7 @@ async def worker() -> None:
     async def txn_metadata(self, txn: Transaction) -> Tuple[bytes, bytes]:
         if await self.offchain.is_under_dual_attestation_limit(txn.currency, txn.amount):
             if txn.refund_diem_txn_version and txn.refund_reason:
-                return self.diem_account.refund_metadata(txn.refund_diem_txn_version, txn.refund_reason)  # pyre-ignore
+                return self.diem_account.refund_metadata(txn.refund_diem_txn_version, txn.refund_reason)
             if txn.subaddress_hex:
                 return self.diem_account.general_metadata(txn.subaddress(), str(txn.payee))
             if txn.reference_id:
diff --git a/src/diem/testing/miniwallet/app/models.py b/src/diem/testing/miniwallet/app/models.py
index 7c47b0f8..5e56ce42 100644
--- a/src/diem/testing/miniwallet/app/models.py
+++ b/src/diem/testing/miniwallet/app/models.py
@@ -26,7 +26,7 @@ def __post_init__(self) -> None:
         self.diem_id = create_diem_id(self.id, str(self.vasp_domain)) if self.vasp_domain else None
 
     def kyc_data_object(self) -> offchain.KycDataObject:
-        return self.kyc_data if self.kyc_data else offchain.individual_kyc_data()  # pyre-ignore
+        return self.kyc_data if self.kyc_data else offchain.individual_kyc_data()
 
 
 @dataclass
diff --git a/src/diem/testing/suites/basic/test_create_test_account.py b/src/diem/testing/suites/basic/test_create_test_account.py
index e14dbead..e5991455 100644
--- a/src/diem/testing/suites/basic/test_create_test_account.py
+++ b/src/diem/testing/suites/basic/test_create_test_account.py
@@ -26,13 +26,7 @@ async def test_create_an_account_with_initial_deposit_balances(
     assert await account.balance(currency) == amount
 
 
-@pytest.mark.parametrize(  # pyre-ignore
-    "kyc_data",
-    [
-        offchain.individual_kyc_data(),
-        offchain.entity_kyc_data(),
-    ],
-)
+@pytest.mark.parametrize("kyc_data", [offchain.individual_kyc_data(), offchain.entity_kyc_data()])
 async def test_create_an_account_with_minimum_valid_kyc_data(
     target_client: RestClient, kyc_data: offchain.KycDataObject
 ) -> None:
diff --git a/src/diem/testing/suites/basic/test_receive_payment.py b/src/diem/testing/suites/basic/test_receive_payment.py
index 110d3e4b..7da15be8 100644
--- a/src/diem/testing/suites/basic/test_receive_payment.py
+++ b/src/diem/testing/suites/basic/test_receive_payment.py
@@ -74,10 +74,7 @@ async def test_receive_payment_with_invalid_metadata(
 
 @pytest.mark.parametrize("amount", [10_000, 1200_000, 125550_000])
 async def test_receive_payment_with_general_metadata_and_valid_from_and_to_subaddresses(
-    stub_client: RestClient,
-    target_client: RestClient,
-    currency: str,
-    amount: int,
+    stub_client: RestClient, target_client: RestClient, currency: str, amount: int
 ) -> None:
     """
     Test Plan:
@@ -101,7 +98,7 @@ async def test_receive_payment_with_general_metadata_and_valid_from_and_to_subad
         await sender_account.log_events()
 
 
-@pytest.mark.parametrize(  # pyre-ignore
+@pytest.mark.parametrize(
     "invalid_to_subaddress", [None, b"", b"bb4a3ba109a3175f", b"subaddress_more_than_8_bytes", b"too_short"]
 )
 async def test_receive_payment_with_general_metadata_and_invalid_to_subaddress(
@@ -163,7 +160,7 @@ async def test_receive_payment_with_general_metadata_and_invalid_to_subaddress(
         await sender_account.log_events()
 
 
-@pytest.mark.parametrize(  # pyre-ignore
+@pytest.mark.parametrize(
     "invalid_from_subaddress", [None, b"", b"bb4a3ba109a3175f", b"subaddress_more_than_8_bytes", b"too_short"]
 )
 async def test_receive_payment_with_general_metadata_and_invalid_from_subaddress(
@@ -216,7 +213,7 @@ async def test_receive_payment_with_general_metadata_and_invalid_from_subaddress
 @pytest.mark.parametrize(
     "invalid_from_subaddress", [None, b"", b"bb4a3ba109a3175f", b"subaddress_more_than_8_bytes", b"too_short"]
 )
-@pytest.mark.parametrize(  # pyre-ignore
+@pytest.mark.parametrize(
     "invalid_to_subaddress", [None, b"", b"bb4a3ba109a3175f", b"subaddress_more_than_8_bytes", b"too_short"]
 )
 async def test_receive_payment_with_general_metadata_and_invalid_subaddresses(
diff --git a/src/diem/testing/suites/offchainv2/test_payment_command.py b/src/diem/testing/suites/offchainv2/test_payment_command.py
index 5832b3f0..3fe785b6 100644
--- a/src/diem/testing/suites/offchainv2/test_payment_command.py
+++ b/src/diem/testing/suites/offchainv2/test_payment_command.py
@@ -264,11 +264,7 @@ async def test_payment_command_contains_invalid_actor_metadata_item_type(
 
 
 async def test_replay_the_same_payment_command(
-    currency: str,
-    travel_rule_threshold: int,
-    stub_wallet_app: App,
-    stub_client: RestClient,
-    target_client: RestClient,
+    currency: str, travel_rule_threshold: int, stub_wallet_app: App, stub_client: RestClient, target_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -285,9 +281,7 @@ async def test_replay_the_same_payment_command(
     target_kyc = await target_client.get_kyc_sample()
     stub_kyc = await stub_client.get_kyc_sample()
     sender_account = await stub_client.create_account(
-        balances={currency: travel_rule_threshold},
-        kyc_data=target_kyc.minimum,
-        disable_background_tasks=True,
+        balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum, disable_background_tasks=True
     )
     receiver_account = await target_client.create_account(kyc_data=stub_kyc.minimum)
     try:
@@ -306,11 +300,7 @@ async def test_replay_the_same_payment_command(
 
 
 async def test_payment_command_sender_kyc_data_can_only_be_written_once(
-    currency: str,
-    travel_rule_threshold: int,
-    stub_wallet_app: App,
-    stub_client: RestClient,
-    target_client: RestClient,
+    currency: str, travel_rule_threshold: int, stub_wallet_app: App, stub_client: RestClient, target_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -330,9 +320,7 @@ async def test_payment_command_sender_kyc_data_can_only_be_written_once(
     target_kyc = await target_client.get_kyc_sample()
     stub_kyc = await stub_client.get_kyc_sample()
     sender_account = await stub_client.create_account(
-        balances={currency: travel_rule_threshold},
-        kyc_data=target_kyc.minimum,
-        disable_background_tasks=True,
+        balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum, disable_background_tasks=True
     )
     receiver_account = await target_client.create_account(kyc_data=stub_kyc.minimum)
     try:
@@ -393,9 +381,7 @@ async def test_payment_command_sender_address_can_only_be_written_once(
     target_kyc = await target_client.get_kyc_sample()
     stub_kyc = await stub_client.get_kyc_sample()
     sender_account = await stub_client.create_account(
-        balances={currency: travel_rule_threshold},
-        kyc_data=target_kyc.minimum,
-        disable_background_tasks=True,
+        balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum, disable_background_tasks=True
     )
     receiver_account = await target_client.create_account(kyc_data=stub_kyc.minimum)
     try:
@@ -431,14 +417,7 @@ async def test_payment_command_sender_address_can_only_be_written_once(
         await sender_account.log_events()
 
 
-@pytest.mark.parametrize(
-    "field_name",
-    [
-        "currency",
-        "amount",
-        "timestamp",
-    ],
-)
+@pytest.mark.parametrize("field_name", ["currency", "amount", "timestamp"])
 async def test_payment_command_action_can_only_be_written_once(
     currency: str,
     travel_rule_threshold: int,
@@ -466,9 +445,7 @@ async def test_payment_command_action_can_only_be_written_once(
     target_kyc = await target_client.get_kyc_sample()
     stub_kyc = await stub_client.get_kyc_sample()
     sender_account = await stub_client.create_account(
-        balances={currency: travel_rule_threshold},
-        kyc_data=target_kyc.minimum,
-        disable_background_tasks=True,
+        balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum, disable_background_tasks=True
     )
     receiver_account = await target_client.create_account(kyc_data=stub_kyc.minimum)
     try:
@@ -486,6 +463,7 @@ async def test_payment_command_action_can_only_be_written_once(
         offchain_cmd = updated_cmd.to_offchain_command()
 
         # update action field value
+        field_value = ""
         if field_name == "currency":
             field_value = "XDX" if offchain_cmd.payment.action.currency == "XUS" else "XUS"
         elif field_name == "amount":
@@ -535,12 +513,7 @@ async def assert_payment_command_field_error(
     set_field(request, full_field_name, field_value)
 
     status_code, resp = await send_request_json(
-        diem_client,
-        stub_config.account,
-        sender_address,
-        receiver_address,
-        json.dumps(request),
-        hrp,
+        diem_client, stub_config.account, sender_address, receiver_address, json.dumps(request), hrp
     )
     assert status_code == 400
     assert resp.status == "failure"
diff --git a/src/diem/testing/suites/offchainv2/test_receive_payment.py b/src/diem/testing/suites/offchainv2/test_receive_payment.py
index 7d7165d0..c13643bc 100644
--- a/src/diem/testing/suites/offchainv2/test_receive_payment.py
+++ b/src/diem/testing/suites/offchainv2/test_receive_payment.py
@@ -13,10 +13,7 @@
 
 
 async def test_receive_payment_with_travel_rule_metadata_and_valid_reference_id(
-    stub_client: RestClient,
-    target_client: RestClient,
-    currency: str,
-    travel_rule_threshold: int,
+    stub_client: RestClient, target_client: RestClient, currency: str, travel_rule_threshold: int
 ) -> None:
     """
     Test Plan:
@@ -42,9 +39,7 @@ async def test_receive_payment_with_travel_rule_metadata_and_valid_reference_id(
         await sender_account.log_events()
 
 
-@pytest.mark.parametrize(  # pyre-ignore
-    "invalid_ref_id", [None, "", "ref_id_is_not_uuid", "6cd81d79-f041-4f28-867f-e4d54950833e"]
-)
+@pytest.mark.parametrize("invalid_ref_id", [None, "", "ref_id_is_not_uuid", "6cd81d79-f041-4f28-867f-e4d54950833e"])
 async def test_receive_payment_with_travel_rule_metadata_and_invalid_reference_id(
     stub_client: RestClient,
     target_client: RestClient,
@@ -115,10 +110,7 @@ async def test_receive_payment_with_travel_rule_metadata_and_invalid_reference_i
 
 
 async def test_receive_payment_meets_travel_rule_threshold_both_kyc_data_evaluations_are_accepted(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -134,8 +126,7 @@ async def test_receive_payment_meets_travel_rule_threshold_both_kyc_data_evaluat
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.minimum,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.minimum),
         payment_command_states=["S_INIT", "R_SEND", "READY"],
@@ -145,11 +136,7 @@ async def test_receive_payment_meets_travel_rule_threshold_both_kyc_data_evaluat
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_rejected_by_the_receiver(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
-    hrp: str,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient, hrp: str
 ) -> None:
     """
     Test Plan:
@@ -164,10 +151,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_re
     target_kyc = await target_client.get_kyc_sample()
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
-        sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.reject,
-        ),
+        sender=await stub_client.create_account(balances={currency: travel_rule_threshold}, kyc_data=target_kyc.reject),
         receiver=await target_client.create_account(kyc_data=stub_kyc.minimum),
         payment_command_states=["S_INIT", "R_ABORT"],
         currency=currency,
@@ -176,10 +160,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_re
 
 
 async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_rejected_by_the_sender(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -195,8 +176,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.minimum,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.reject),
         payment_command_states=["S_INIT", "R_SEND", "S_ABORT"],
@@ -206,10 +186,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_soft_match_then_accepted_after_reviewing_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -225,8 +202,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.soft_match,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.soft_match
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.minimum),
         payment_command_states=["S_INIT", "R_SOFT", "S_SOFT_SEND", "R_SEND", "READY"],
@@ -236,10 +212,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
 
 
 async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_soft_match_then_accepted_after_reviewing_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -255,8 +228,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.minimum,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.soft_match),
         payment_command_states=["S_INIT", "R_SEND", "S_SOFT", "R_SOFT_SEND", "READY"],
@@ -266,10 +238,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_soft_match_then_rejected_after_reviewing_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -285,8 +254,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.soft_reject,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.soft_reject
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.minimum),
         payment_command_states=["S_INIT", "R_SOFT", "S_SOFT_SEND", "R_ABORT"],
@@ -296,10 +264,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
 
 
 async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_soft_match_then_rejected_after_reviewing_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -315,8 +280,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.minimum,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.minimum
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.soft_reject),
         payment_command_states=["S_INIT", "R_SEND", "S_SOFT", "R_SOFT_SEND", "S_ABORT"],
@@ -326,10 +290,7 @@ async def test_receive_payment_meets_travel_rule_threshold_receiver_kyc_data_is_
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_soft_match_then_receiver_aborts_for_sending_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -358,10 +319,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_and_receiver_kyc_data_are_soft_match_then_accepted_after_reviewing_additional_kyc_data(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -377,8 +335,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_and_receiver_k
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.soft_match,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.soft_match
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.soft_match),
         payment_command_states=["S_INIT", "R_SOFT", "S_SOFT_SEND", "R_SEND", "S_SOFT", "R_SOFT_SEND", "READY"],
@@ -388,10 +345,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_and_receiver_k
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_soft_match_and_accepted_receiver_kyc_data_is_rejected(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -407,8 +361,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.soft_match,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.soft_match
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.reject),
         payment_command_states=["S_INIT", "R_SOFT", "S_SOFT_SEND", "R_SEND", "S_ABORT"],
@@ -418,10 +371,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
 
 
 async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_soft_match_and_accepted_receiver_kyc_data_is_soft_match_and_rejected(
-    currency: str,
-    travel_rule_threshold: int,
-    target_client: RestClient,
-    stub_client: RestClient,
+    currency: str, travel_rule_threshold: int, target_client: RestClient, stub_client: RestClient
 ) -> None:
     """
     Test Plan:
@@ -437,8 +387,7 @@ async def test_receive_payment_meets_travel_rule_threshold_sender_kyc_data_is_so
     stub_kyc = await stub_client.get_kyc_sample()
     await receive_payment_meets_travel_rule_threshold(
         sender=await stub_client.create_account(
-            balances={currency: travel_rule_threshold},
-            kyc_data=target_kyc.soft_match,
+            balances={currency: travel_rule_threshold}, kyc_data=target_kyc.soft_match
         ),
         receiver=await target_client.create_account(kyc_data=stub_kyc.soft_reject),
         payment_command_states=["S_INIT", "R_SOFT", "S_SOFT_SEND", "R_SEND", "S_SOFT", "R_SOFT_SEND", "S_ABORT"],
diff --git a/src/diem/utils.py b/src/diem/utils.py
index 76e354f6..c7c2c071 100644
--- a/src/diem/utils.py
+++ b/src/diem/utils.py
@@ -3,15 +3,13 @@
 
 """Utilities for data type converting, construction and hashing."""
 
+import sys
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey, Ed25519PrivateKey
 import hashlib, typing, time, socket, asyncio
 
 from . import diem_types, jsonrpc, stdlib
-from .constants import (
-    SUB_ADDRESS_LEN,
-    DIEM_HASH_PREFIX,
-)
+from .constants import SUB_ADDRESS_LEN, DIEM_HASH_PREFIX
 
 
 class InvalidAccountAddressError(Exception):
@@ -225,8 +223,9 @@ def shutdown_event_loop(loop: asyncio.events.AbstractEventLoop) -> None:
     try:
         asyncio.runners._cancel_all_tasks(loop)  # pyre-ignore
         loop.run_until_complete(loop.shutdown_asyncgens())
-        if hasattr(loop, "shutdown_default_executor"):
-            loop.run_until_complete(getattr(loop, "shutdown_default_executor")())
+        if sys.version_info >= (3, 9):
+            if hasattr(loop, "shutdown_default_executor"):
+                loop.run_until_complete(getattr(loop, "shutdown_default_executor")())
     finally:
         asyncio.set_event_loop(None)
         loop.close()
@@ -238,7 +237,7 @@ async def with_retry(coroutine, max_retries=5, delay_secs=0.1, exception=Excepti
         tries += 1
         try:
             return await coroutine()
-        except exception as e:  # pyre-ignore
+        except exception as e:
             if tries < max_retries:
                 # simplest backoff strategy: tries * delay
                 await asyncio.sleep(delay_secs * tries)