void rbt_preorder(rbt r, void f(char *s,colour_t c)) { if(r == NULL){ return; }else{ f(r->key,r->colour); rbt_preorder(r->left,f); rbt_preorder(r->right,f); } }
void rbt_preorder(rbt r, void f(char *s)) { if (NULL == r) return; f(r->key); rbt_preorder(r->left, f); rbt_preorder(r->right, f); }