== and != Operators
	Notice why a “first” and “second” shouldn’t be data members: bool list::operator == (const list & l2) const {   node * first = head;   node * second = l2.head;   while (first && second && first->obj == second->obj) {     first = first->next;     second = second->next;   }   if (first || second) return FALSE;   return TRUE; } Evaluate the efficiency of the following: bool list::operator != (const list & l2) const {   return !(*this == l2);   }