Not able to complete the tutorial

Hi, I have a newbie question.

I am currently walking through the calculator language tutorial. I nearly completed the "Implementing generator" section. I have come into trouble in the place where it says "Now, let's generate our language and take a look at what happens with the sandbox model. As you can see, MPS generates exactly the code that we wanted". Actually, it does not (and that is the problem). I probably made a mistake somewhere.

Here is the generated code of the update() method:

    int i_a = 0;
    int i_b = 0;
    int i_c = 0;
    try {
       = Integer.parseInt(inputField_a.getText());
       = Integer.parseInt(inputField_b.getText());
       = Integer.parseInt(inputField_c.getText());
    } catch (NumberFormatException e) {
    }
    outputField_a.setText("" + (2 + 3 + 9 + ));

Not surprisingly, the error message says:

calculator/sandbox/sandbox/MyCalc.java : Syntax error on token "=", delete this token (line: 57)

Could please anybody give a tip where things could go wrong? As far as I can see, my code (is it code in MPS? I do not know) looks the same as it does on the images from the tutorial.

BTW, I really have no idea what is that "reduction rule" for InputFieldReference and what is the purpose of that code fragment {int i; i = 1 + <TF ->$[i] TF}. I did that rule anyway.

I have MPS 2.0.1.

Best regards,

Dmitry