Can't compare NoneType with float/int

[epenelope]

python-playground$ python3 largest-smallest.py
Enter a number: 10
Traceback (most recent call last):
File "largest-smallest.py", line 10, in
if num >= largest:
TypeError: '>=' not supported between instances of 'float' and 'NoneType'

[Asaurus1]

What is the expected result for this operation? Should it be True or False? In Python 3, float(None) gives a type error, so there's no implicit conversion that could be performed.