human
I wrote the below code

    def fun(x):
        for i in range((10 ** 4)):
            x = ((x + x) / 2.0)
        return np.sum(x)
    with tictoc():
        grad(fun)(1.0)

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def fan_out_fan_in():