class_docstr: Base class for observers
class_docstr_tok: ["Base","class","for","observers"]
code: def __init__(self, observing_keys: List[str]):
      super().__init__()
      assert isinstance(observing_keys, list)
      self.observing_keys = observing_keys
  
file_path: ReAgent/reagent/core/tracker.py
imports: import functools
  import logging
  from typing import Dict, List, Type
  import torch
label_desc: Use image node_id 1 to create a new Observer object  with example: obj = Observer(observing_keys)