code: def construct_single_input_tokens_and_segment_ids(
      input_tokens: List[str], tokenizer, feat_spec: FeaturizationSpec
  ):
      special_tokens_count = 2  # CLS, SEP
  
      (input_tokens,) = truncate_sequences(
          tokens_ls=[input_tokens],
          max_length=feat_spec.max_seq_length - special_tokens_count,
      )
  
      return add_cls_token(
          unpadded_tokens=input_tokens + [tokenizer.sep_token],
          unpadded_segment_ids=(
              [feat_spec.sequence_a_segment_id]
              + [feat_spec.sequence_a_segment_id] * (len(input_tokens))
          ),
          tokenizer=tokenizer,
          feat_spec=feat_spec,
      )
  
imports: import numpy
  from dataclasses import dataclass
  from typing import List, NamedTuple
  from jiant.tasks.core import FeaturizationSpec
  from jiant.tasks.utils import truncate_sequences, pad_to_max_seq_length
  from jiant.utils.python.datastructures import BiMap
label_desc: Use image node_id 3 for calling a global function with example usage: construct_single_input_tokens_and_segment_ids(input_tokens, tokenizer, feat_spec) and returns: add_cls_token