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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 _assert_relation_does_not_exists(self):
 """ Check if a relation with the current related_name doesn't already exists for the related model """

        relations = self.database._relations[self.related_to]
        existing = [r for r in relations if r[2] == self.related_name]
        if existing:
            error = ("The related name defined for the field '%s.%s', named '%s', already exists "
                     "on the model '%s' (tied to the field '%s.%s')")
            raise ImplementationError(error % (self._model.__name__, self.name, self.related_name,
                                      self.related_to, existing[0][1], existing[0][0]))