code: def __init__(self, length):
      super().__init__()
      self.counter = Counter()
      self.finished = set()
      self.length = length
  
imports: from collections import Counter
  import gym
  import numpy
  from tianshou.data import Batch, Collector
  from tianshou.policy import BasePolicy
  from torch.utils.data import DataLoader, Dataset, DistributedSampler
  from qlib.rl.utils.finite_env import LogWriter, FiniteDummyVectorEnv, FiniteShmemVectorEnv, FiniteSubprocVectorEnv, check_nan_observation, generate_nan_observation
label_desc: Use image node_id 1 to create a new MetricTracker object from inherited base classes: LogWriter with example: obj = MetricTracker(length)