How Do I Make It On Mouse Click

Im trying to make a game and this is part of the script im using i need help changing

function Attack() {
if (sindel_mc.jump) {
sindel_mc.gotoAndStop(“airkick”);
} else {
if (Key.isDown(Key.DOWN)) {
sindel_mc.gotoAndStop(“crouchkick”);
} else {
sindel_mc.gotoAndStop(“punch”);
}
}
}

Where is it key down, i am trying to change it so that instead of key down its on mouse click