PYTHON

__call__ python

#this will allow you to treat object as function
class Test:
  def __init__(self, num):
    self.num = num
  def __call__(self, inp):
    print(self.num*inp)

#create an instance of Test class
obj = Test(5)
obj(3) #15

__call__ python

def add(a,b):
    return a + b

__call__() python

class Foo:
    def __call__(self, a, b, c):
        # ...

x = Foo()
x(1, 2, 3) # __call__