human
I wrote the below code

    class my_function2(Function, ):
        def fdiff(self, argindex=1):
            return (- sin(self.args[0]))
        @classmethod
        def eval(cls, arg):
            arg = sympify(arg)
            if (arg == 0):
                return sympify(1)
    assert (my_function2(x).series(x, 0, 10) == cos(x).series(x, 0, 10))

What's a good function header?

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

def test_function_series2():