code: def uniquetwig(self, ps=None):
          
          if ps is None:
              ps = self._bundle
  
          if ps is None:
              return self.twig
          return ps._uniquetwig(self.twig)
docs: see also :meth:`twig`
  
          Determine the shortest (more-or-less) twig which will point
          to this single Parameter in a given parent :class:`ParameterSet`
  
          :parameter ps: :class:`ParameterSet` in which the returned
              uniquetwig will point to this Parameter.  If not provided
              or None this will default to the parent :class:`phoebe.frontend.bundle.Bundle`,
              if available.
          :return: uniquetwig
          :rtype: str