- int degree(symbol const &s) const;
- int ldegree(symbol const &s) const;
- ex coeff(symbol const &s, int const n=1) const;
+ int degree(const symbol &s) const;
+ int ldegree(const symbol &s) const;
+ ex coeff(const symbol &s, int n=1) const;
+ ex collect(const symbol &s) const;