def is_locked(self, key):
check_not_none(key, "<STR_LIT>")<EOL>key_data = self._to_data(key)<EOL>return self._encode_invoke_on_key(multi_map_is_locked_codec, key_data, key=key_data)<EOL>
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.