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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def normal_curve_single(obj, u, normalize):
 """ Evaluates the curve normal vector at the input parameter, u. Curve normal is calculated from the 2nd derivative of the curve at the input parameter, u. The output returns a list containing the starting point (i.e. origin) of the vector and the vector itself. :param obj: input curve :type obj: abstract.Curve :param u: parameter :type u: float :param normalize: if True, the returned vector is converted to a unit vector :type normalize: bool :return: a list containing "point" and "vector" pairs :rtype: tuple """

    # 2nd derivative of the curve gives the normal
    ders = obj.derivatives(u, 2)

    point = ders[0]
    vector = linalg.vector_normalize(ders[2]) if normalize else ders[2]

    return tuple(point), tuple(vector)