class_docstr: Abstract base class for QA Datasets with common utility methods 
class_docstr_tok: ["Abstract","base","class","for","QA","Datasets","with","common","utility","methods"]
code: def load_features_from_cache(cached_filename):
      logging.info(f"loading from {cached_filename}")
      with open(cached_filename, "rb") as reader:
          features = pickle.load(reader)
  
      return features
  
imports: import collections
  import pickle
  from functools import lru_cache
  from typing import List
  import psutil
  import torch
  from nemo.collections.nlp.data.data_utils import is_whitespace
  from nemo.collections.nlp.data.question_answering.data_processor.qa_processing import EVALUATION_MODE, INFERENCE_MODE, TRAINING_MODE
  from nemo.core.classes import Dataset
  from nemo.utils import logging
label_desc: Use image node_id 4 for calling the QADataset obj's underlying member method code with example usage: obj.load_features_from_cache(cached_filename) and returns: features