Recusively exports object values to a dict

        :return: `dict`of values

def to_dict(self):
        """
        Recusively exports object values to a dict

        :return: `dict`of values
        """
        if not hasattr(self, '_fields'):
            return self.__dict__
        result = dict()
        for field_name, field in self._fields.items():
            if isinstance(field, xmlmap.NodeField):
                obj = getattr(self, field_name)
                if obj is None:
                    result[field_name] = None
                elif not hasattr(obj, 'to_dict'):
                    result[field_name] = obj.__dict__
                else:
                    result[field_name] = obj.to_dict()
            elif isinstance(field, xmlmap.NodeListField):
                objs = getattr(self, field_name)
                result[field_name] = list()
                for obj in objs:
                    if not hasattr(obj, 'to_dict'):
                        result[field_name].append(obj.__dict__)
                    else:
                        result[field_name].append(obj.to_dict())
            else:
                result[field_name] = getattr(self, field_name)
        return result