docs: def get_id(self, grp):
          """
          Return a hash of the tuple of indices that specify the group
          """
          thehash = hex(hash(grp))
          if ISPY3:  # use default encoding to get bytes
              thehash = thehash.encode()
          return self.cache.get(grp, hashlib.sha1(thehash).hexdigest())