Divisor + Divisor -- sum of two Divisors

i1 : Q = quadricSurface(ZZ/101[x,y,z,w]);

i2 : C = divisor({1,0},Q);

i3 : D = divisor({0,1},Q);

i4 : C+D

o4 = {1, 1}

o4 : Divisor