def hypot2(x, y):
    """Compute the norm, I{squared} M{x**2 + y**2}.

       @arg x: Argument (C{scalar}).
       @arg y: Argument (C{scalar}).

       @return: B{C{x}}C{**2 + }B{C{y}}C{**2} (C{float}).
    """
    x, y = x ** 2, y ** 2
    if x < y:
        x, y = y, x
    if y:
        x *= 1 + y / x
    return x
