how to make a click detector door?

a = Instance.new("ClickDetector")
a.Parent=game.Workspace.Part
variable = true

function onClick()
    if(variable=true)then
    script.Parent.Transparency=0.5
    script.Parent.CanCollide=false
    variable=false
    end
    if(variable=false)then
    script.Parent.Transparency=0
    script.Parent.CanCollide=true
    variable=true
end

script.Parent.ClickDetector.MouseClick:connect(onClick)

The code above should create a one button open and close door, not tested however.