def METHOD_NAME(self, class_, func):
    b1 = class_(3.14)
    b2 = class_(2)
    bmul = float(b1)*float(b2)
    bmul2 = 2*float(b1)
    assert b1*b2 == approx(bmul)
    assert b2*b1 == approx(bmul)
    assert 2*b1 == approx(bmul2)
    assert b1*2 == approx(bmul2)