--unasync option to find non-async functions/methods

[simonw]

I realize that you can use --function to find all async-and-not-async functions, and --async to find all async functions... but there's no way to find just not-async functions.

[simonw]

Given this list of existing options:

  --async                    Filter async functions
  --function                 Filter functions
  --class                    Filter classes
  --documented               Filter functions with docstrings
  --undocumented             Filter functions without docstrings
  --typed                    Filter functions with type annotations
  --untyped                  Filter functions without type annotations

I think --unasync is the right name, for consistency with --undocumented and --untyped.