[Tutor] How to assert a float?

[Willi Richert]

Hi Tutor,

How do you assert the following:

============================
import math

def log2(x):
    return math.log(x)/math.log(2.0)

assert 2**log2(5)==5.0
============================

2**log2(5) yields 4.9999999999999991 which is not 5.0

To round is also not very wise. Do you know how one can assert floats? 

Thanks
willi