from Threading import Thread

def thread_fn():
    # do stuff here. 
    
num_threads = 10
for i in range(num_threads):
    t = Thread(target=thread_fn, args=[]) # args[] contains function arguments
    t.start()                             # thread is now running!
    threads.append(t)                     # hold onto it for it later

for t in threads:
    t.join()                              # waits for each t to finish