pub unsafe fn to_byte(&self, position: usize) -> u8 {
        let shifted = self.to_u64() >> (position * 8);
        (shifted & 0xFF) as u8
    }
Interpreting the slot as a byte array,
returns the byte at a given index.
Say we have the usize `0xAAFF`, which is `43775` decimal.
Byte at position `0` is `0xFF`, `1` is `0xAA`;
the rest of the bits are zeroed, so positions `2..=8` would be `0x00`.
# Safety
Caller must ensure that the slot in question is a byte.
passerine-qualm/src/slot.rs