@Nullable
  public static String parseQName(Lexer lexer) {
    String name;
    if (lexer.getTokenType() == XPathTokenTypes.NCNAME) {
      name = lexer.getTokenText();
      lexer.advance();
      if (lexer.getTokenType() == XPathTokenTypes.COL) {
        lexer.advance();
        assert lexer.getTokenType() == XPathTokenTypes.NCNAME;
        name += (":" + lexer.getTokenText());
        lexer.advance();
      }
    } else {
      name = null;
    }
    return name;
  }
@Nullable
  public static String parseQName(Lexer lexer)