Best way to stop forever loop on event - Python

subtraction.py

In [1]: run = 1

In [2]: event = 17

In [3]: def a():
   ...:     if event == 17:
   ...:         run = 0
   ...:         

In [4]: def b():
   ...:     run = event - 17
   ...:     

In [5]: def c():
   ...:     run = event ^ 17
   ...:     

In [6]: %timeit a()
10000000 loops, best of 3: 108 ns per loop

In [7]: %timeit b()
10000000 loops, best of 3: 88.4 ns per loop

In [8]: %timeit c()
10000000 loops, best of 3: 97 ns per loop