private static boolean prefixExpressionsAreEquivalent(@NotNull GrUnaryExpression prefixExp1,
                                                        @NotNull GrUnaryExpression prefixExp2) {
    final IElementType sign1 = prefixExp1.getOperationTokenType();
    final IElementType sign2 = prefixExp2.getOperationTokenType();
    if (sign1 != sign2) {
      return false;
    }
    final GrExpression operand1 = prefixExp1.getOperand();
    final GrExpression operand2 = prefixExp2.getOperand();
    return expressionsAreEquivalent(operand1, operand2);
  }
private static boolean prefixExpressionsAreEquivalent(@NotNull GrUnaryExpression prefixExp1,
                                                        @NotNull GrUnaryExpression prefixExp2)