puttableSlice

    fn puttableSlice(q: *const TypeErasedQueue) ?[]u8 {
        const unwrapped_index = q.start + q.len;
        const wrapped_index, const overflow = @subWithOverflow(unwrapped_index, q.buffer.len);
        const slice = switch (overflow) {
            1 => q.buffer[unwrapped_index..],
            0 => q.buffer[wrapped_index..q.start],
        };
        return if (slice.len > 0) slice else null;
    }