private static boolean postfixExpressionsAreEquivalent(@NotNull GrUnaryExpression postfixExp1,
                                                         @NotNull GrUnaryExpression postfixExp2) {
    final IElementType sign1 = postfixExp1.getOperationTokenType();
    final IElementType sign2 = postfixExp2.getOperationTokenType();
    if (sign1 != sign2) {
      return false;
    }
    final GrExpression operand1 = postfixExp1.getOperand();
    final GrExpression operand2 = postfixExp2.getOperand();
    return expressionsAreEquivalent(operand1, operand2);
  }
private static boolean postfixExpressionsAreEquivalent(@NotNull GrUnaryExpression postfixExp1,
                                                         @NotNull GrUnaryExpression postfixExp2)