provide a non-destructive mechanism to determine if a sink/stream are paired #2368

Job	Run time
cargo test (ubuntu-latest)	2m 51s
cargo +1.36 build (futures-{core, io, sink})	5m 31s
cargo test (macos-latest)	6m 39s
cargo bench	2m 20s
cargo +stable build	45s
cargo test (windows-latest)	4m 22s
cargo hack check --feature-powerset	3m 17s
cargo +beta build	1m 2s
cargo test (ubuntu-latest, aarch64-unknown-linux-gnu)	4m 11s
cargo +nightly build	1m 1s
cargo minimal-versions build	39s
cargo test (ubuntu-latest, armv7-unknown-linux-gnueabihf)	8m 20s
cargo test (ubuntu-latest, armv5te-unknown-linux-gnueabi)	6m 33s
cargo build --target thumbv7m-none-eabi	28s
cargo +1.56 build	3m 21s
cargo test (ubuntu-latest, i686-unknown-linux-gnu)	3m 20s
cargo build --target thumbv6m-none-eabi	49s
cargo clippy	24s
codegen	41s
cargo doc	32s
cargo fmt	7s
cargo miri test	7m 24s
cargo test -Z sanitizer=address	4m 33s
cargo test -Z sanitizer=memory	3m 20s
cargo test -Z sanitizer=thread	3m 10s
	1h 15m 40s

Provide feedback