code: def truncate_seq_pair(tokens_a, tokens_b, max_num_tokens):
      """Truncates a pair of sequences to a maximum sequence length."""
      while True:
          total_length = len(tokens_a) + len(tokens_b)
          if total_length <= max_num_tokens:
              break
  
          trunc_tokens = (
              tokens_a if len(tokens_a) > len(tokens_b) else tokens_b
          )
          assert len(trunc_tokens) >= 1
  
          # We want to sometimes truncate from the front and sometimes from the
          # back to add more randomness and avoid biases.
          if random.random() < 0.5:
              del trunc_tokens[0]
          else:
              trunc_tokens.pop()
  
imports: import argparse
  import logging
  import io
  import os
  import glob
  import collections
  import warnings
  import random
  import time
  from multiprocessing import Pool
  import numpy
  from gluonnlp.models.bert import BertModel, BertForPretrain, get_pretrained_bert
  import gluonnlp
label_desc: Use image node_id 9 for calling a global function with example usage: truncate_seq_pair(tokens_a, tokens_b, max_num_tokens) without return types