code: def __getitem__(self, item):
      if len(self.deque) == 0:  # 如果没有任何缓存的内容，说明还没有写入，直接返回0
          return 0
      assert isinstance(item, int), "Only int index allowed."
      assert (
          self.count - len(self.deque) <= item < self.count
      ), f"Only keep {len(self.deque)} history index."
      index = len(self.deque) - (self.count - item)
      return self.deque[index]
  
file_path: fastNLP/fastNLP/core/samplers/utils.py
imports: from array import array
  from typing import Sequence
  from collections import deque
label_desc: Use image node_id 2 for calling the NumConsumedSamplesArray obj's underlying member method code with example usage: obj.__getitem__(item) and returns: self, int