itertools vs purity

[sparkz_alot]

I haven't really used itertools so I thought I would try the 'accumulate' attribute against the equivalent math formula. Is it possible that the formula is truly that fast (faster than time itself  ?) Or is there a better way to time this.

import itertools
import time


a_list = []
for member in range(1, 1000001):
    a_list.append(member)
list_length = len(a_list)


def accum(a_list):
    acc = itertools.accumulate(a_list)
    for n in acc:
        total = n
    print("Total from itertools = ", total)
    return


def by_formula(list_length):
    same_result = list_length * (list_length + 1) / 2
    print("\nTotal from formula = ", int(same_result))
    return


start_1 = time.time()
first = accum(a_list)
print('first took {0:0.7f} seconds'.format(time.time() - start_1))

start_2 = time.time()
second = by_formula(list_length)
print('second took {0:0.10f} seconds'.format(time.time() - start_2))

Output:
Total from itertools =  500000500000
first took 0.0312371 seconds

Total from formula =  500000500000
second took 0.0000000000 seconds

Process finished with exit code 0