code: def decode(tokens):
      """Decode a list of tokens to a unicode string.
  
      Args:
        tokens: a list of Unicode strings
      Returns:
        a unicode string
      """
      token_is_alnum = [t[0] in _ALPHANUMERIC_CHAR_SET for t in tokens]
      ret = []
      for i, token in enumerate(tokens):
          if i > 0 and token_is_alnum[i - 1] and token_is_alnum[i]:
              ret.append(" ")
          ret.append(token)
      return "".join(ret)
  
file_path: trax/trax/data/tokenizer.py
imports: import collections
  import sys
  import unicodedata
  from absl import logging
  import six
  import tensorflow
label_desc: Use image node_id 2 for calling a global function with example usage: decode(tokens) and returns: str