Test for object identity should be 'is not' (E714)

Tests for object identity should use the form x is not None rather than not x is None. The former example is simply more readable.

Anti-pattern

if not user is None:
    print(user.name)

Best practice

if user is not None:
    print(user.name)

Additional links

• https://www.python.org/dev/peps/pep-0008/#programming-recommendations