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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_children_metadata(self):
 """Gets the metadata for children. return: (osid.Metadata) - metadata for the children *compliance: mandatory -- This method must be implemented.* """

        metadata = dict(self._mdata['children'])
        metadata.update({'existing_children_values': self._my_map['childIds']})
        return Metadata(**metadata)