E713.md

Pattern: Missing use of not in for membership test

Issue: -

Description

Tests for membership should use the form x not in the_list rather than not x in the_list. The former example is more readable.

Example of incorrect code:

my_list = [1, 2, 3]
if not num in my_list:
    print(num)

Example of correct code:

my_list = [1, 2, 3]
if num not in my_list:
    print(num)

Further Reading

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