func Signal(signal os.Signal) {
	trackedSessionsMutex.Lock()
	defer trackedSessionsMutex.Unlock()
	for _, session := range trackedSessions {
		session.Signal(signal)
	}
}
func Signal(signal os.Signal) {
	trackedSessionsMutex.Lock()
	defer trackedSessionsMutex.Unlock()
	for _, session := range trackedSessions {
		session.Signal(signal)
	}
}
/*
Signal sends the passed in signal to all the processes started by Run.
It does not wait for the processes to exit.

If any of the processes already exited, Signal returns silently.
*/