useful (but not common known) python idioms

python idioms

# useful eg, for recursive functions such as merge sort or binary tree building/traversal in which sometimes the fn must return one of two portions of some container (a sequence, tree node, etc.)

def fnx(a):
	if a % 2 == 0:
		x = 45
		y = None
	else:
		x = None
		y = 3
	return (x or y) + 2