import threading
import time
import random

m = threading.Lock()

def draw(txt):
    for i in range(10):
        t = random.randrange(100, 1000)
        time.sleep(t/1000.)

        m.acquire()
        print(txt)
        m.release()

def main():
    t1 = threading.Thread(target=draw, args=("Heads",))
    t1.start()
    t2 = threading.Thread(target=draw, args=("Tails",))
    t2.start()
    t1.join()
    t2.join()

if __name__ == "__main__":
    main()