def test_function_series1():

    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)

    #Test that the taylor series is correct
    assert my_function(x).series(x, 0, 10) == sin(x).series(x, 0, 10)
    assert limit(my_function(x)/x, x, 0) == 1
Create our new "sin" function.
dataset/ETHPy150Open sympy/sympy/sympy/functions/elementary/tests/test_interface.py/test_function_series1