key :: Var -> Var -> (Var,Var)
key x y 
    | x < y = (x,y)
    | otherwise = (y,x)
key :: Var -> Var -> (Var,Var)
key x y 
    | x < y = (x,y)
    | otherwise = (y,x)
key x y 
    | x < y = (x,y)
    | otherwise = (y,x)