docs: def MakeTokenRegex(meta_left, meta_right):
      """Return a (compiled) regular expression for tokenization.
  
    Args:
      meta_left, meta_right: e.g. '{' and '}'
  
    - The regular expressions are memoized.
    - This function is public so the syntax highlighter can use it.
    """
      key = meta_left, meta_right
      if key not in _token_re_cache:
          # - Need () grouping for re.split
          # - The first character must be a non-space.  This allows us to ignore
          # literals like function() { return 1; } when
          # - There must be at least one (non-space) character inside {}
          _token_re_cache[key] = re.compile(
              r'(' +
              re.escape(meta_left) +
              r'\S.*?' +
              re.escape(meta_right) +
              r')')
      return _token_re_cache[key]