code: def _tokenize_mteval_13a(segment):
      r
  
      norm = segment.rstrip()
  
      norm = norm.replace('<skipped>', '')
      norm = norm.replace('-\n', '')
      norm = norm.replace('\n', ' ')
      norm = norm.replace('&quot;', '"')
      norm = norm.replace('&amp;', '&')
      norm = norm.replace('&lt;', '<')
      norm = norm.replace('&gt;', '>')
  
      norm = u' {} '.format(norm)
      norm = re.sub(r'([\{-\~\[-\` -\&\(-\+\:-\@\/])', ' \\1 ', norm)
      norm = re.sub(r'([^0-9])([\.,])', '\\1 \\2 ', norm)
      norm = re.sub(r'([\.,])([^0-9])', ' \\1 \\2', norm)
      norm = re.sub(r'([0-9])(-)', '\\1 \\2 ', norm)
      norm = re.sub(r'\s+', ' ', norm)
      norm = re.sub(r'^\s+', '', norm)
      norm = re.sub(r'\s+$', '', norm)
  
      return norm
docs: r"""
      Tokenizes a string following the tokenizer in mteval-v13a.pl.
      See https://github.com/moses-smt/mosesdecoder/"
             "blob/master/scripts/generic/mteval-v14.pl#L917-L942
      Parameters
      ----------
      segment: str
          A string to be tokenized
  
      Returns
      -------
      The tokenized string