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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def initialize_fields(self):
 """ The dict self.base_fields is a model instance at this point. Turn it into an instance attribute on this meta class. Also intitialize any other special fields if needed in sub-classes. :return: None """

        for field in dir(self):
            obj = getattr(self, field)
            if isinstance(obj, Field):
                self._meta.fields[field] = obj