* Hello! I'm new to embedded Rust, and I'm exploring the stm32f3xx-hal. I was wondering why the FLASH peripheral is needed when setting RCC's configuration register like so:

```
let p = pac::Peripherals::take().unwrap();
let flash = p.FLASH.constrain();
let rcc = p.RCC.constrain()
let clocks = rcc.cfgr.freeze(&mut flash.acr);
```