Locking mechanism for synchronization of a Thread

lock.py

from threading import Lock, Thread
lock = Lock()
value = 1

def add_one():
   global value
   lock.acquire()
   value += 1
   lock.release()

def add_two():
   global value
   lock.acquire()
   value += 2
   lock.release()

threads = []
for func in [add_one, add_two]:
   threads.append(Thread(target=func))
   threads[-1].start()

for thread in threads:
   """
   Waits for threads to complete before moving on with the main
   """
   thread.join()

print(value)