Hm, it doesn't seem to work like that. I tried a couple of different ways but I'm always getting this error:
```
error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
  --> src/main.rs:84:39
   |
84 |         let _first_half = circ_buffer.peek(|_buf, half| {
   |                                       ^^^^ doesn't have a size known at compile-time
   |
   = help: the trait `Sized` is not implemented for `[u8]`
```