| This error occurs because you tried to mutably borrow a non-mutable variable. | |
| Erroneous code example: | |
| ```compile_fail,E0596 | |
| let x = 1; | |
| let y = &mut x; // error: cannot borrow mutably | |
| ``` | |
| In here, `x` isn't mutable, so when we try to mutably borrow it in `y`, it | |
| fails. To fix this error, you need to make `x` mutable: | |
| ``` | |
| let mut x = 1; | |
| let y = &mut x; // ok! | |
| ``` |