code: def __len__(self) -> int:
      if self.drop_last:
          return len(self.sampler) // self.batch_size
      else:
          return (
              len(self.sampler) + self.batch_size - 1
          ) // self.batch_size
  
file_path: fastNLP/tests/helpers/datasets/normal_data.py
imports: import numpy
  import random
label_desc: Use image node_id 3 for calling the NormalBatchSampler obj's underlying member method code with example usage: obj.__len__() and returns: unknown, unknown