{"ast_node_type":"variable","tokens":[{"end":62,"kind":"keyword","start":0,"text":"if"}]}
        if let UseSpans::ClosureUse { args_span, .. } = self {
    pub(super) fn args_subdiag(self, err: &mut Diag<'_>, f: impl FnOnce(Span) -> CaptureArgLabel) {
            err.subdiagnostic(f(args_span));