private static String getAddendum(String expressionText, PsiElement context) {
      if (expressionText.startsWith("-")) {
        final String negatedExpressionText = expressionText.substring(1);
        final Object lhConstant = computeConstant(negatedExpressionText, context);
        if (lhConstant != null) {
          return " - " + lhConstant.toString();
        }
        return " + (" + expressionText + ")";
      }
      return " + " + expressionText;
    }
private static String getAddendum(String expressionText, PsiElement context)