Why do I get this error:Expressions in a statement must be only executed by their side effects?

Questions & Answers
1

var prefabBullet:Transform;
var shootForce:float;
private var ammo:float;
private var shoot:float;

function Start () {

ammo = 5;
shoot = 1;
}

function Update () 
{
	if (ammo == 0)
	{
	(shoot == 0);	
	}
    
	if (shoot == 1 && (Input.GetMouseButtonDown(2)))
	{
		var	instanceBullet = Instantiate(prefabBullet, transform.position, Quaternion.identity);
		instanceBullet.rigidbody.AddForce(transform.forward * shootForce);
		ammo -=1;
	}
	
	
}
function OnGUI () {
    GUI.Label (Rect (10, 10, 100, 20),ammo.ToString());
}

Its at this part
if (ammo == 0)
{
(shoot == 0);
}

2

if (ammo == 0)
{
shoot = 0;
}