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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 _get_default_mapping(self, obj):
 """Return default mapping if there are no special needs."""

        mapping = {v: k for k, v in obj.TYPE_MAPPING.items()}
        mapping.update({
            fields.Email: text_type,
            fields.Dict: dict,
            fields.Url: text_type,
            fields.List: list,
            fields.LocalDateTime: datetime.datetime,
            fields.Nested: '_from_nested_schema',
        })
        return mapping