def kill_raspistill(*args):
 subprocess.Popen(['killall', 'raspistill'], stdout=subprocess.DEVNULL, stderr=subprocess.STDOUT)

def kill_raspistill ( * args ) : subprocess . Popen ( [ 'killall' , 'raspistill' ] , stdout = subprocess . DEVNULL , stderr = subprocess . STDOUT )
kill any previously running raspistill process .