id: no-identity-operator-on-literals
valid:
  - "if x is None:"
  - "if x is not None:"
  - "if x is y:"  # both are variables
  - "if obj is SingletonClass.instance:"  # pattern
invalid:
  - "if 1 is '1':"
  - "if x is 'literal':"
  - "if 'foo' is x:"
  - "if x is not 42:"
  - "if x is True:"
  - "if x is not False:"
  - "if x is []:"  # list literal