Function child_watch_source_new

pub fn child_watch_source_new<F>(
    pid: Pid,
    name: Option<&str>,
    priority: Priority,
    func: F,
) -> Source
where
    F: FnMut(Pid, i32) + Send + 'static,

Adds a closure to be called by the main loop the returned Source is attached to when a child process exits.

func will be called when pid exits