I want to make calculations with inputs from 2 different Textfields and put the output in a Text. See code:

```
@State var input1: String = ""

@State var input2: String = ""

var calculation : Double {
    let calculationProduct = Double(input1) * Double(input2)
    return calculationProduct
}

var body: some View {
VStack{
 TextField("", text: $input1)
 TextField("", text: $input1)

Text("\(calculation)")
}

```

The problem is the code won't compile, i get different compile errors, for example: "Binary operator '\*' cannot be applied to two 'Double?' operands".

What goes wrong?