The __exit__() method doesn't conform PEP 8.

PEP 8: """Be consistent in return statements. Either all return statements in a function should return an expression, or none of them should. 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)."""

The __exit__() method has explicit "return False", bare "return", and implicit "return" at the end of the method. Together with different styles in different "except" clauses this makes it slightly hard to read.