pyflink中Transform里的map的使用方法是什么？

class MyMapFunction(MapFunction):
  def open(self, runtime_context: RuntimeContext):
    # 数据量
    self.count_state = runtime_context.get_state(ValueStateDescriptor("count_state", Types.INT()))

    def map(self, value: Row):
      self.count_state.update((self.count_state.value() or 0) + 1)  # count_state += 1
      return value

data_stream = data_stream.key_by(lambda x: x["id"]) \
    .map(MyMapFunction(), output_type=Types.TUPLE([Types.STRING(), Types.STRING()]))