code: def validate_internal_deps(self):
          
          for node in self.node:
              if ('target_obj' not in self.node[node]
                      and node not in self.crossrefs):
                  raise error.BrokenGraph('Missing target: %s referenced from %s'
                                          ' but not defined there.' %
                                          (node, self.name))
docs: Freak out if there are missing local references.