const symbol &s = ex_to<symbol>(r.lhs());
new_seq.push_back(expair(Order(_ex1), numeric(std::min(x.ldegree(s), order))));
return pseries(r, new_seq);
const symbol &s = ex_to<symbol>(r.lhs());
new_seq.push_back(expair(Order(_ex1), numeric(std::min(x.ldegree(s), order))));
return pseries(r, new_seq);