code: def get_property_chain_axioms(self, nid):
          
          pcas = self.all_property_chain_axioms
          if pcas is not None:
              return [x for x in pcas if x.predicate_id == nid]
          else:
              return []
docs: Retrieves property chain axioms for a class id
  
          Arguments
          ---------
          nid : str
               Node identifier for relation to be queried
  
          Returns
          -------
          PropertyChainAxiom