Duration

    pub const Duration = struct {
        raw: Io.Duration,
        clock: Clock,

        /// Waits until a specified amount of time has passed on `clock`.
        ///
        /// See also:
        /// * `Io.sleep`
        /// * `Clock.Timestamp.wait`
        /// * `Timeout.sleep`
        pub fn sleep(duration: Clock.Duration, io: Io) Cancelable!void {
            return io.vtable.sleep(io.userdata, .{ .duration = duration });
        }
    }