Optimize this code snippet in Python.
data = [1, 2, 3, 4, 5, 6]
sum = 0

for num in data:
    sum = sum + num
data = [1, 2, 3, 4, 5, 6]
sum = 0

sum = sum + sum(data) # This is more efficient than iterating through the whole list with a `for` loop.