{"ast_node_type":"other","tokens":[{"end":111,"kind":"keyword","start":0,"text":"///"}]}
    /// This function returns a `Result<&Expr, &Expr>` - either way, it returns the `Expr` whose span should be
    ///
    /// reported as an error. If it is `Ok`, then it means it refined successful. If it is `Err`, then it may be