Brain Flak Macro

Write [Brain-Flak] code inside rust. You can pass a vector for input. The brain_flak macro will expand to stack manipulation.

```rust use brainflakmacro::brain_flak;

let mut vec: Vec = vec![20, 5]; brainflak! { &mut vec => // multiplication ([({}<(({}(<()>))<>)<>>)<>]){({}[()]<(({})<({}{})>)>)<>}{}{}<>{}{}{}<> } asserteq!(vec![100], vec); ```

Why

I was about to make [brainfuck macro] but it already exist. A random guy from some random discord server suggested Brain-Flak instead. It's choice of using balanced brackets make it easy enough for just using macro_rules (No).