Function tick 

pub fn tick<F>(duration: Duration, f: F) -> Cmd
where
    F: FnOnce(Instant) -> Message + Send + 'static,

Command that ticks after a duration.

The tick runs for the full duration from when it’s invoked. To create periodic ticks, return another tick command from your update function when handling the tick message.

Example

use bubbletea::{Cmd, tick, Message};
use std::time::{Duration, Instant};

struct TickMsg(Instant);

fn do_tick() -> Cmd {
    tick(Duration::from_secs(1), |t| Message::new(TickMsg(t)))
}