add.py

#!/usr/bin/env python

from __future__ import print_function
import time

s = ""

def f():
    global s
    s += "a"

t = time.time()

for i in xrange(1000000000):
    f()
    step = 100000
    if i % step == 0:
        print("{:.4}us".format((time.time() - t) / step * 1000000))
        t = time.time()

# vim: set ts=4 sw=4 et: