import time

def dec1(input_function):
    def output_function(arg):
        start = time.perf_counter()
        input_function(arg)
        end = time.perf_counter() - start
        print(end)
        return input_function(arg)
    return output_function




class SecondDecoratorTest():
    to_do_inner = lambda a: a

    def to_do(self,a):
        return self.to_do_inner(a)


obj1 = SecondDecoratorTest()
obj1.to_do_inner = lambda a: [i*i for i in a]
result = obj1.to_do([1,2,3,4])
print(result)

obj1.to_do = dec1(obj1.to_do)

result2 = obj1.to_do([1,2,3,4])
print(result2)