code: def is_locked(self, key):
          
          check_not_none(key, "key can't be None")
          key_data = self._to_data(key)
          return self._encode_invoke_on_key(multi_map_is_locked_codec, key_data, key=key_data)
docs: Checks the lock for the specified key. If the lock is acquired, returns ``true``. Otherwise, returns false.
  
          **Warning: This method uses __hash__ and __eq__ methods of binary form of the key, not the actual implementations
          of __hash__ and __eq__ defined in key's class.**
  
          :param key: (object), the key that is checked for lock.
          :return: (bool), ``true`` if lock is acquired, false otherwise.