Async iterators & context managers

async for and async with for streaming I/O.

Anything that streams (DB cursors, HTTP responses, file-like) can implement __aiter__ / __anext__ and __aenter__ / __aexit__. Combine with contextlib.asynccontextmanager to write async with helpers in a few lines.

main.py

Output

Press Run to execute.

Expected output

open db
db 0
db 1
db 2
close db