AjRools.Expert.World.RetractFact C# (CSharp) Метод

        public void RetractFact(Fact fact)
        {
            if (fact is IsFact)
            {
                IsFact isfact = (IsFact)fact;

                object current = this.context.GetValue(isfact.Name);

                if (current == null || !current.Equals(isfact.Value))
                    throw new InvalidOperationException();

                this.context.SetValue(isfact.Name, null);
                this.retracted.Enqueue(fact);
                return;
            }

            if (!this.facts.Contains(fact))
                throw new InvalidOperationException();

            this.facts.Remove(fact);
            this.retracted.Enqueue(fact);
        }