code: def make_d2p_id(self):
          
  
          attributes = [self.onset, self.frequency]
          assoc_id = self.make_association_id(
              self.definedby, self.disease_id, self.rel, self.phenotype_id, attributes)
  
          return assoc_id
docs: Make an association id for phenotypic associations with disease
          that is defined by:
          source of association + disease + relationship + phenotype
          + onset + frequency
  
          :return: