code: def execute_on_key(self, key, entry_processor):
          
          check_not_none(key, "key can't be None")
          key_data = self._to_data(key)
          return self._execute_on_key_internal(key_data, entry_processor)
docs: Applies the user defined EntryProcessor to the entry mapped by the key. Returns the object which is the result
          of EntryProcessor's process method.
  
          :param key: (object), specified key for the entry to be processed.
          :param entry_processor: (object), A stateful serializable object which represents the EntryProcessor defined on
              server side.
              This object must have a serializable EntryProcessor counter part registered on server side with the actual
              ``org.hazelcast.map.EntryProcessor`` implementation.
          :return: (object), result of entry process.