Using “or” in a python for loop to define default sequence

Question

I have seen somewhere this usage of a for loop:

def func(seq=None):
    for i in seq or [1, 2, 3]:
       print i

func([3, 4, 5])  # Will print 3, 4, 5
func()           


        

Answer 1

No! It's the operator priority! or before in…
Precedence, §6.15.
So seq or [1, 2, 3] is evaluated before entering the loop. And seq is None.