Python ictionary without empty fields

DictNoNone.py

class DictNoNone(dict):
    """Delete empty fields from dictionary """
    def __init__(self, initial_dict={}):
        for key in initial_dict:
            self.__setitem__(key, initial_dict[key])

    def __setitem__(self, key, value):
        if key in self or value:
            dict.__setitem__(self, key, value)