public override IEnumerable <IVerb> getVerbs()
        {
            IEnumerable <IVerb> verbs = new IVerb[] { producer };

            verbs = verbs.Union(producer.getVerbs());
            return(verbs);
            //-            VerificationResultSummaryVerb depends on objects mentioned by producer,
            //-but the necessary verbs haven't been mentioned. Is it sufficient for
            //-the upstream guy (BoogieAsmVerificationObligationList) to ... hopefully ...
            //-mention them? (Hopefully because he might only be incompletely queried,
            //-since he's not actually dependent on the verbs he's advertising.)
            //-Maybe we should provide a way for his complete() method to push the
            //-verbs into the cache.
        }
        public override IEnumerable<IVerb> getVerbs()
        {
            IEnumerable<IVerb> verbs = new IVerb[] { this.producer };

            verbs = verbs.Union(this.producer.getVerbs());
            return verbs;

            // VerificationResultSummaryVerb depends on objects mentioned by producer,
            // but the necessary verbs haven't been mentioned. Is it sufficient for
            // the upstream guy (BoogieAsmVerificationObligationList) to ... hopefully ...
            // mention them? (Hopefully because he might only be incompletely queried,
            // since he's not actually dependent on the verbs he's advertising.)
            // Maybe we should provide a way for his complete() method to push the
            // verbs into the cache.
        }