#### Note: this error code is no longer emitted by the compiler.
Closures cannot mutate immutable captured variables.
Erroneous code example:
```compile_fail,E0594
let x = 3; // error: closure cannot assign to immutable local variable `x`
let mut c = || { x += 1 };
```
Make the variable binding mutable:
```
let mut x = 3; // ok!
let mut c = || { x += 1 };
```