def test_pow():
u = Unit(length, factor=10)
assert u.pow(0) == 1
assert u.pow(1) == u
assert u.pow(2) == Unit(length.pow(2), factor=100)
assert u.pow(-1) == Unit(length.pow(-1), factor=0.1)
def test_div():
u = Unit(length, factor=10)
assert u.rdiv(1) == u.pow(-1)
assert u.div(1) == u
assert u.div(Unit(time, factor=2)) == Unit(length.div(time), factor=5)
assert u.div(Unit(length, factor=2)) == 5
