sage: p=2 sage: F4=GF(p^4) sage: R.<x,y,z>=PolynomialRing(F4) sage: C=Curve(y^3-zx^2-z^2x) sage: len(C.rational_points()) 9 sage: L=C.L_polynomial() I get AttributeError: 'ProjectivePlaneCurve_finite_field_with_category' object has no attribute 'L_polynomial'