{"ast_node_type":"variable","tokens":[{"end":58,"kind":"keyword","start":0,"text":"let"}]}
        let mut typeck = self.typeck_results.borrow_mut();
        debug!("write_ty({:?}, {:?}) in fcx {}", id, self.resolve_vars_if_possible(ty), self.tag());
        let mut node_ty = typeck.node_types_mut();