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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 _check_relation(self, relation):
 """Raise a `ValueError` if `relation` is not allowed among the possible values. """

        selection = [val[0] for val in self.selection]
        if relation not in selection:
            raise ValueError(
                ("The value '{value}' supplied doesn't match with the possible"
                 " values '{selection}' for the '{field_name}' field").format(
                     value=relation,
                     selection=selection,
                     field_name=self.name,
                 ))
        return relation