code: def __init__(self, key: str):
      super().__init__(key)
      self.values: List[float] = []
  
imports: import logging
  from collections import deque
  from typing import Any, Callable, Deque, Dict, List, Optional
  import numpy
  import torch
  from reagent.core.tensorboardX import SummaryWriterContext
  from reagent.core.tracker import Aggregator
label_desc: Use image node_id 1 to create a new MeanAggregator object from inherited base classes: TensorAggregator with example: obj = MeanAggregator(key)