{"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":"self.instantiate_opt(tcx,"}]}
        self.instantiate_opt(tcx, args).unwrap_or(self)
    pub fn instantiate(self, tcx: TyCtxt<'tcx>, args: ty::GenericArgsRef<'tcx>) -> Self {
    }