private void parseBindingSequence(PsiBuilder builder) {
    do {
      if (builder.getTokenType() == XPathTokenTypes.COMMA) {
        builder.advanceLexer();
      }

      final PsiBuilder.Marker bindingSeq = builder.mark();
      parseVariableDecl(builder);

      checkMatches(builder, XPath2TokenTypes.IN, XPathBundle.message("parsing.error.in.expected"));

      if (!parseExprSingle(builder)) {
        builder.error(XPathBundle.message("parsing.error.expression.expected"));
      }
      bindingSeq.done(XPath2ElementTypes.BINDING_SEQ);
    } while (builder.getTokenType() == XPathTokenTypes.COMMA);
  }
private void parseBindingSequence(PsiBuilder builder)