class_docstr: Class to represent a relationship between dataframes
  
  See Also:
      :class:`.EntitySet`
class_docstr_tok: ["Class","to","represent","a","relationship","between","dataframes","See","Also",":",":","class",":","`",".EntitySet","`"]
docstr: Is there any other relationship with same parent and child dataframes?
docstr_tok: ["Is","there","any","other","relationship","with","same","parent","and","child","dataframes","?"]
code: def _is_unique(self):
      """Is there any other relationship with same parent and child dataframes?"""
      es = self.entityset
      relationships = es.get_forward_relationships(
          self._child_dataframe_name
      )
      n = len(
          [
              r
              for r in relationships
              if r._parent_dataframe_name == self._parent_dataframe_name
          ],
      )
  
      assert n > 0, "This relationship is missing from the entityset"
  
      return n == 1
  
label_desc: Use image node_id 13 for calling the Relationship obj's underlying member method code with example usage: obj._is_unique() and returns: unknown