:x: Problematic code:
def foo(x): if x: return 1
:heavy_check_mark: Correct code:
def foo(x): if x: return 1 return None
Either all return statements in a function should return an expression, or none of them should. According to PEP8 , if any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable).