Function subscribe 

pub fn subscribe() -> Result<Watcher, Error>

Subscribes to changes in the system theme mode.

Returns a Watcher that receives a new Mode each time the OS theme changes. Only mode transitions are emitted, and the watcher’s background thread (where used) stops when the Watcher is dropped.

Example

use dark_light::{ Error, Mode };

fn main() -> Result<(), Error> {
    let watcher = dark_light::subscribe()?;
    for mode in watcher.iter() {
        match mode {
            Mode::Dark => {},
            Mode::Light => {},
            Mode::Unspecified => {},
        }
    }
    Ok(())
}