not-in-test (E713)

Derived from the pycodestyle linter.

Fix is always available.

What it does

Checks for membership tests using not {element} in {collection}.

Why is this bad?

Testing membership with {element} not in {collection} is more readable.

Example

Z = not X in Y
if not X.B in Y:
    pass

Use instead:

Z = X not in Y
if X.B not in Y:
    pass