code: def input_tokens(self):
      batch_input_tokens = 0
      for req in self.reqs:
          batch_input_tokens += req.input_len
      return batch_input_tokens
  
imports: from typing import Dict, List, Tuple
  from .sampling_params import SamplingParams
label_desc: Use image node_id 2 for calling the Batch obj's underlying member method code with example usage: obj.input_tokens() and returns: batch_input_tokens