__call__ method. It then behaves similar to a function: class multiplier:
def __init__(self, t):
self.t = t
def __call__(self, v):
return self.t * v
mult_by_4 = multiplier(4)
mult_by_9 = multiplier(9)
print(mult_by_4(5)) # 20
print(mult_by_9(3)) # 27