More coding with movements

Today I have done more coding for moving objects. Here is what I have done


var ship:MovieClip=new Ship ();                         These lines tell flash to look in the Library for something
ship.x=275;                                                 called ship and places it in the co-ordinates listed.
ship.y=200;
addChild(ship);


import flash.events.Event;
import flash.events.KeyboardEvent;

var moveRight:Boolean = false                        These scripts tell flash to keep the commands off.
var moveLeft:Boolean = false
var moveUp:Boolean = false
var moveDown:Boolean = false

stage.addEventListener(Event.ENTER_FRAME, moveSquare)

function moveSquare(event:Event) {

if(moveRight==true) {                             all these commands tell flash to turn the commands on if the
square.x+=3;                                           keys are being pressed down.
}
if(moveLeft==true) {
square.x-=3;
}
if(moveUp==true) {
square.y-=3;
}
if(moveDown==true) {
square.y+=3;
}
}
stage.addEventListener(KeyboardEvent.KEY_DOWN,pressKey);
stage.addEventListener(KeyboardEvent.KEY_UP,stopSquare);

function stopSquare(myevent:KeyboardEvent):void{              These codes are turning off the command
moveLeft=false                                                                    when the buttons arent pressed.
moveRight=false
moveUp=false
moveDown=false

}

function pressKey(myevent:KeyboardEvent):void{
if(myevent.keyCode==Keyboard.RIGHT){
moveRight=true;
}
if(myevent.keyCode==Keyboard.LEFT){
moveLeft=true;
}
if(myevent.keyCode==Keyboard.UP){
moveUp=true;
}
if(myevent.keyCode==Keyboard.DOWN){
moveDown=true;
}



}