import signal

def is_main_thread():
    try:
        # Backup the current signal handler
        back_up = signal.signal(signal.SIGINT, signal.SIG_DFL)
    except ValueError:
        # Only Main Thread can handle signals
        return False
    # Restore signal handler
    signal.signal(signal.SIGINT, back_up)
    return True
print (is_main_thread())