cset_splay
ncsn->csn_left = cset_splay(ncsn->csn_left, ncsn->csn_min - 1);
ncsn->csn_right = cset_splay(ncsn->csn_right,
cs->cs_root = cset_splay(cs->cs_root, ch);
t = cset_splay(t, ch);
x = cset_splay(t->csn_left, ch);
static struct csnode *cset_splay(struct csnode *, wchar_t);
csn = cs->cs_root = cset_splay(cs->cs_root, ch);