{"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"if"}]}
        if let TtElement::Subtree(subtree, subtree_iter) = &t {
        // implement rustc's model. cc https://github.com/rust-lang/rust-analyzer/pull/10623
            if let [tt::TokenTree::Leaf(tt)] = subtree_iter.remaining().flat_tokens() {