code: def unregister_algorithm(self, alg_id):
          
          if alg_id not in self._algorithms:
              raise KeyError('The specified algorithm could not be removed'
                             ' because it is not registered.')
  
          del self._algorithms[alg_id]
          self._valid_algs.remove(alg_id)
docs: Unregisters an Algorithm for use when creating and verifying tokens
          Throws KeyError if algorithm is not registered.