code: def termset_ancestors(self, terms):
          
          ancs = set()
          for term in terms:
              ancs = ancs.union(self.ontology.ancestors(term))
          return ancs.union(set(terms))
docs: reflexive ancestors
  
          Arguments
          ---------
  
            terms - a set or list of class IDs
  
          Returns: set of class IDs