Use shorter name of Iterator

Tools/cases_generator/formatting.py

@@ -1,7 +1,7 @@
-import collections
 import contextlib
 import re
 import typing
+from collections.abc import Iterator
 
 from parsing import StackEffect, Family
 
@@ -59,13 +59,13 @@ def reset_lineno(self) -> None:
             self.set_lineno(self.lineno + 1, self.filename)
 
     @contextlib.contextmanager
-    def indent(self) -> collections.abc.Iterator[None]:
+    def indent(self) -> Iterator[None]:
         self.prefix += "    "
         yield
         self.prefix = self.prefix[:-4]
 
     @contextlib.contextmanager
-    def block(self, head: str, tail: str = "") -> collections.abc.Iterator[None]:
+    def block(self, head: str, tail: str = "") -> Iterator[None]:
         if head:
             self.emit(head + " {")
         else:

Tools/cases_generator/generate_cases.py

@@ -4,13 +4,13 @@
 """
 
 import argparse
-import collections
 import contextlib
 import itertools
 import os
 import posixpath
 import sys
 import typing
+from collections.abc import Iterator
 
 import stacking  # Early import to avoid circular import
 from analysis import Analyzer
@@ -193,9 +193,7 @@ def effect_str(effects: list[StackEffect]) -> str:
         return instr, popped, pushed
 
     @contextlib.contextmanager
-    def metadata_item(
-        self, signature: str, open: str, close: str
-    ) -> collections.abc.Iterator[None]:
+    def metadata_item(self, signature: str, open: str, close: str) -> Iterator[None]:
         self.out.emit("")
         self.out.emit(f"extern {signature};")
         self.out.emit("#ifdef NEED_OPCODE_METADATA")