{"ast_node_type":"variable","tokens":[{"end":45,"kind":"keyword","start":0,"text":"let"}]}
        let iter_next_expr = self.alloc_expr(
            self.alloc_expr(iter_next_fn.map_or(Expr::Missing, Expr::Path), syntax_ptr);
            Expr::Call { callee: iter_next_fn_expr, args: Box::new([iter_expr_mut]) },