class_docstr: RunState is used to save the result of every running step
  Args:
      length (int): the number of fetch result
code: def update(self):
      self.run_time_used = time.time() - self.run_time_begin
      self.run_speed = self.run_step / self.run_time_used
      return self
  
file_path: PaddleHub/paddlehub/compat/task/task_utils.py
imports: import copy
  import time
  from typing import Any
  import paddle.utils.unique_name
label_desc: Use image node_id 3 for calling the RunState obj's underlying member method code with example usage: obj.update() and returns: self