do not subclass built-in classes in python
In short, they will not behave what you think they will. you think dict.get in implemented in python, like:
def get(self, key, default=None):
try:
return self[key]
except KeyError:
return default
However, they dict.get do not call getitem, and they are implemented in c separately, and do not call each other.
so, when you implement geitem, get is not automatically altered! which is very dangerous.
What you need do, subclass collections.abc.Mapping
source:
[1] http://www.kr41.net/2016/03-23-dont_inherit_python_builtin_dict_type.html