code: def path(self):
          
          if len(self.heads) == 1:
              return _fmt_mfs_path(self.heads.keys()[0], self.heads.values()[0])
          else:
              return "(" + "|".join(
                  _fmt_mfs_path(k, v) for (k, v) in self.heads.items()
              ) + ")"
docs: The path attribute returns a stringified, concise representation of
          the MultiFieldSelector.  It can be reversed by the ``from_path``
          constructor.