code: def remove_waiter(self, waiter_handle):
          
  
          spec, waiter = waiter_handle
          self._remove_waiter(spec, waiter)
docs: Remove a message callback.
  
          This call will remove a callback previously registered using
          every_match.
  
          Args:
              waiter_handle (object): The opaque handle returned by the
                  previous call to every_match().