{"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"//"}]}
// * Expr(P<ast::Expr>)                     -> token_tree_to_expr
// link: https://github.com/rust-lang/rust/blob/9ebf47851a357faa4cd97f4b1dc7835f6376e639/src/libsyntax/ext/expand.rs#L141
// * Pat(P<ast::Pat>)                       -> token_tree_to_pat