```
var a: CGFloat!  
var b: CGFloat!  
var c: CGFloat!  

```

After init then 

```
let x = a + b + c

```

The Xcode8 would show 

***Binary operator '+' cannot be applied to operands of type 'CGFloat' and 'CGFloat!'***

guess first add two of them made this Error

Maybe I could use first add one and then add third to fix

But It will change my x to var and not concise as past 

Any Suggestion?

---

*Edit: there must some application scenarios we could faced, I wrote this simple demo just 4 express this issue :)*