def distance_to(self, *args):
        """Return the distance to a rectangle or another point."""
        if not len(args) > 0:
            raise ValueError("at least one parameter must be given")

        x = args[0]
        if len(args) > 1:
            unit = args[1]
        else:
            unit = "px"
        u = {"px": (1.,1.), "in": (1.,72.), "cm": (2.54, 72.),
             "mm": (25.4, 72.)}
        f = u[unit][0] / u[unit][1]
        if type(x) is Point:
            return abs(self - x) * f

# from here on, x is a rectangle
# as a safeguard, make a finite copy of it
        r = Rect(x.top_left, x.top_left)
        r = r | x.bottom_right
        if self in r:
            return 0.0
        if self.x > r.x1:
            if self.y >= r.y1:
                return self.distance_to(r.bottom_right, unit)
            elif self.y <= r.y0:
                return self.distance_to(r.top_right, unit)
            else:
                return (self.x - r.x1) * f
        elif r.x0 <= self.x <= r.x1:
            if self.y >= r.y1:
                return (self.y - r.y1) * f
            else:
                return (r.y0 - self.y) * f
        else:
            if self.y >= r.y1:
                return self.distance_to(r.bottom_left, unit)
            elif self.y <= r.y0:
                return self.distance_to(r.top_left, unit)
            else:
                return (r.x0 - self.x) * f
Return the distance to a rectangle or another point.