struct treenode *new_node(int op, struct treenode *l, struct treenode *r, int exprcount);
struct treenode *new_number(long val, int exprcount);
struct treenode *new_node(int op, struct treenode *l, struct treenode *r, int exprcount);
struct treenode *new_number(long val, int exprcount);