code: def _subword_start_by_joiner(tokens: Sequence[str]) -> Sequence[bool]:
      """Find word start in a subword list marked by joiner."""
      flag = [True] * len(tokens)
      for i, token in enumerate(tokens):
          if token.startswith(SubwordMarker.JOINER) and i != 0:
              flag[i] = False
          if token.endswith(SubwordMarker.JOINER):
              try:
                  flag[i + 1] = False
              except IndexError:
                  print(
                      "Sentence `{}` not correct!".format(
                          " ".join(token)
                      )
                  )
                  raise
      return flag
  
imports: import math
  import numpy
  import torch
  from typing import Sequence, Callable
  from onmt.constants import DefaultTokens, SubwordMarker
  from onmt.transforms import register_transform
  from .transform import Transform
label_desc: Use image node_id 1 for calling a global function with example usage: _subword_start_by_joiner(tokens) and returns: flag