// Add adds a shutdown hook
// and returns hook identificator (key).
Add adds a shutdown hook
and returns hook identificator (key).
// Add adds a shutdown hook // and returns hook identificator ( key ) .
func (s *Shutdown) Add(fn func()) string {
	return s.AddWithParam(func(os.Signal) {
		fn()
	})
}
func ( s * Shutdown ) Add ( fn func ( ) ) string { return s . AddWithParam ( func ( os . Signal ) { fn ( ) } ) }
Add adds a shutdown hook
and returns hook identificator (key).
Add adds a shutdown hook and returns hook identificator ( key ) .