docs: def get_objects(self, subject=None, predicate=None):
          """Returns a generator of objects that correspond to the
          specified subjects and predicates."""
  
          for triple in self.triples:
  
              # Filter out non-matches
              if ((subject and triple['subject'] != subject) or
                  (predicate and triple['predicate'] != predicate)):
                  continue
  
              yield triple['object']