{"ast_node_type":"variable","tokens":[{"end":21,"kind":"keyword","start":0,"text":"let"}]}
        let yielded =
    fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
            opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span));