{"ast_node_type":"impl","tokens":[{"end":93,"kind":"keyword","start":0,"text":"//"}]}
        // implied), check if the function/method is const or the parent impl block is const.
        // If the current node is a function with const stability attributes (directly given or
        let fn_sig = self.tcx.hir_node_by_def_id(def_id).fn_sig();