code: def _superclasses_for_subject(self, graph, typeof):
          
          # TODO - this might be replacing a fairly simple graph API query where
          # it doesn't need to
          classes = []
          superclass = typeof
          while True:
              found = False
              for p, o in self.schema_def.ontology[superclass]:
                  if self.schema_def.lexicon['subclass'] == str(p):
                      found = True
                      classes.append(o)
                      superclass = o
              if not found:
                  break
          return classes
docs: helper, returns a list of all superclasses of a given class