code: def CloseExpression(clean_lines, linenum, pos):
    
  
    line = clean_lines.elided[linenum]
    if (line[pos] not in '({[<') or Match(r'<[<=]', line[pos:]):
      return (line, clean_lines.NumLines(), -1)
  
    # Check first line
    (end_pos, stack) = FindEndOfExpressionInLine(line, pos, [])
    if end_pos > -1:
      return (line, linenum, end_pos)
  
    # Continue scanning forward
    while stack and linenum < clean_lines.NumLines() - 1:
      linenum += 1
      line = clean_lines.elided[linenum]
      (end_pos, stack) = FindEndOfExpressionInLine(line, 0, stack)
      if end_pos > -1:
        return (line, linenum, end_pos)
  
    # Did not find end of expression before end of file, give up
    return (line, clean_lines.NumLines(), -1)
docs: If input points to ( or { or [ or <, finds the position that closes it.
  
    If lines[linenum][pos] points to a '(' or '{' or '[' or '<', finds the
    linenum/pos that correspond to the closing of the expression.
  
    TODO(unknown): cpplint spends a fair bit of time matching parentheses.
    Ideally we would want to index all opening and closing parentheses once
    and have CloseExpression be just a simple lookup, but due to preprocessor
    tricks, this is not so easy.
  
    Args:
      clean_lines: A CleansedLines instance containing the file.
      linenum: The number of the line to check.
      pos: A position on the line.
  
    Returns:
      A tuple (line, linenum, pos) pointer *past* the closing brace, or
      (line, len(lines), -1) if we never find a close.  Note we ignore
      strings and comments when matching; and the line we return is the
      'cleansed' line at linenum.