code: def cache(self, link, nav):
          '''Stores a navigator in the identity map for the current
          api. Can take a link or a bare uri'''
          if link is None:
              return  # We don't cache navigators without a Link
          elif hasattr(link, 'uri'):
              self.id_map[link.uri] = nav
          else:
              self.id_map[link] = naf cache(self, link, nav):
          '''Stores a navigator in the identity map for the current
          api. Can take a link or a bare uri'''
          if link is None:
              return  # We don't cache navigators without a Link
          elif hasattr(link, 'uri'):
              self.id_map[link.uri] = nav
          else:
              self.id_map[link] = nav
docs: Stores a navigator in the identity map for the current
          api. Can take a link or a bare uri