【求教】这段书上的代码，删掉def __call__(self): 会有什么后果

删掉后会报
self._target(*self._args, **self._kwargs)
TypeError: 'ThreadFunc' object is not callable
代码如下
import threading
from time import sleep,ctime
loops=[4,2]
class ThreadFunc:
def __init__(self,func,args,name=''):
self.func=func
self.args=args
self.name=name
def __call__(self):
self.func(*self.args)
def loop(nloop,nsec):
print('start loop',nloop,'at:',ctime())
sleep(nsec)
print("loop",nloop,'done at:',ctime())
def main():
print('starting at:',ctime())
threads=[]
nloops=range(len(loops))
for i in nloops:
t=threading.Thread(target=ThreadFunc(loop,(i,loops[i]),loop.__name__))
threads.append(t)
for i in nloops:
threads[i].start()
for i in nloops:
threads[i].join()
print ('ALL DONE AT:',ctime())
if __name__=='__main__':
main()