Area or Perimeter

You are given the length and width of a 4-sided polygon. The polygon can either be a rectangle or a square. If it is a square, return its area. If it is a rectangle, return its perimeter.

My code:

def area_or_perimeter(l , w):
    if l == w:
        return l * l
    elif l != w:
        return (l+w)*2

And that's the best solution among all users:

def area_or_perimeter(l, w):
    return l * w if l == w else (l + w) * 2