{"ast_node_type":"variable","tokens":[{"end":89,"kind":"keyword","start":0,"text":"let"}]}
        let pending_obligations = self.fulfillment_cx.borrow_mut().pending_obligations();
    fn create_coercion_graph(&self) -> VecGraph<ty::TyVid, true> {
        debug!("create_coercion_graph: pending_obligations={:?}", pending_obligations);