'Converts this refinement to a token string safe to be used in HTML.
The format of this string may change.
Returns:
A token string safe to be used in HTML for this facet refinement.'

def ToTokenString(self):

    facet_refinement = search_service_pb.FacetRefinement()
    self._CopyToProtocolBuffer(facet_refinement)
    return base64.b64encode(facet_refinement.SerializeToString())
