human
I wrote the below code

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

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

def test_function_series1():