def expensive_function(x):
	print("called the very expensive function, that will be $2")
	return x*x + x
	
data = [4, 7, 3, 7, 2, 3, 4, 7, 3, 1, 1 ,1]


result = [
	(x, expensive)
	for x in data
	for expensive in [expensive_function(x)] #alias
	if expensive > 3
]

print(result)