add_child
fragment->add_child(std::move(wrapper));
newroot->add_child(std::move(fragment));
root->add_child(node::create_special_node("__symbols__", symbols));
root->add_child(node::create_special_node("__fixups__", symbols));
n->add_child(node::create_special_node(path, symbols));
root->add_child(std::move(local_fixups));