Macro format_bytes 

macro_rules! format_bytes {
    ($slice:expr $(,)? ) => { ... };
    (hex, $slice:expr $(,)? ) => { ... };
    (bin, $slice:expr $(,)? ) => { ... };
    ($slice:expr, $sep:literal $(,)? ) => { ... };
    (hex, $slice:expr, $sep:literal $(,)? ) => { ... };
    (bin, $slice:expr, $sep:literal $(,)? ) => { ... };
}

colorfully formats a slice or vector of u8 as hex => binary => decimal (=> char (if ascii))