code: def __iter__(self):
      if self.need_reinitialize:
          self._index = 0
          if self.shuffle:
              random.shuffle(self._data)
      else:
          self.need_reinitialize = True
  
      return self
  
file_path: fastNLP/tests/helpers/datasets/normal_data.py
imports: import numpy
  import random
label_desc: Use image node_id 2 for calling the NormalSampler obj's underlying member method code with example usage: obj.__iter__() and returns: self