Robert Oliveira

The __contains__ method is actually redundant and causes a strange behavior documented in the additional tests in this pull request.

platform.version() doesn't return the python version. platform.python_version() or platform.python_version_tuple() would also work but sys.version_info is more popular.

Once checked that __contains__ is not required by the tests in its docstrings we can remove it.

The calls to the upper-class methods should use dict instead of object. Maybe pedantic as there is no impact and it is unlikely to have the __getattribute__, __delattr__, and __setattr__...

Change tests comparing results with dictionaries as suggested by the doctests documentation: https://docs.python.org/3.5/library/doctest.html#warnings

The method __getattr__ is called as a fallback method for __getattribute__ hence the removed call always fails and is unnecessary.