Toggle gui visibility?

Hello
I have a script that makes gui texture appear when an input is held, but I want it to toggle instead. How would I do this

Here’s the script:

var aimTexture : GUITexture;
function Update() {
    // Only enable aim texture when 'Aim' button is not pressed.
    // In this case I have used 'Shift' key for this.
    if (Input.GetButton("Aim") || Input.GetKey("Fire2"))
        aimTexture.enabled = true;
    else
        aimTexture.enabled = false;
}

Well first off there is an answer hub for specific questions, you should use it.
Try the .GetButtonDown() functions they only activate when you press the button down. GetButton() returns true if current button state is Down().

So overall you would have something like this

if( input.GetButtonDown(“whatever”){
aimTexture.enabled = !aimTexture.enabled;
}