code: def word_start_finder(
      ignore_subword=False, is_joiner=False
  ) -> Callable:
      """Return callable to find all word start in the token list."""
      if not ignore_subword:
          if is_joiner:
              return _subword_start_by_joiner
          else:
              return _subword_start_by_spacer
      else:
          return lambda tokens: [True] * len(tokens)
  
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 3 for calling a global function with example usage: word_start_finder(ignore_subword, is_joiner) and returns: function, _subword_start_by_joiner, _subword_start_by_spacer