l,r;

tree_copy(s;t) [tree(t)] {
  local i, j, ii, jj;
  if(t == NULL) s = t;
  else { 
    i = t->l;
    j = t->r;
    tree_copy(ii;i);
    tree_copy(jj;j);
    s = new();
    s->l = ii;
    s->r = jj;
  }
} [tree(s) * tree(t)]

tree_deallocate(t) [tree(t)] {
  local i, j;
  if(t == NULL) {}
  else {
    i = t->l;
    j = t->r;
    tree_deallocate(i);
    tree_deallocate(j);
    dispose(t);
  }
} [emp]