twochilds.c

/*
allocate a child and move down

parent -> null
^

to
	
parent -> new child
          ^
*/
void typ_recur(struct typ **typ)
{
	(*typ)->child = typ_alloc();
	*typ = (*typ)->child;
}

/*
allocate a child and move down

parent -> old child
^

to

parent -> new child -> old child
          ^
*/
void typ_recur2(struct typ **typ)
{
	struct typ *child = (*typ)->child;
	(*typ)->child = typ_alloc();
	(*typ)->child->child = child;
	*typ = (*typ)->child;
}