ex evalf(int level=0) const;
ex subs(const lst & ls, const lst & lr) const;
ex eval_indexed(const basic & i) const;
+ ex add_indexed(const ex & self, const ex & other) const;
bool contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const;
protected:
unsigned return_type(void) const { return return_types::noncommutative; };