public void Add(Printer.Abstract.Printer printer)
        {
            if (ReferenceEquals(Set, null))
            {
                Set = new HashSet <Printer.Abstract.Printer>();
            }

            if (ReferenceEquals(printer, null))
            {
                throw new ArgumentNullException(nameof(printer));
            }

            Set.Add(printer);
        }
        public bool Remove(Printer.Abstract.Printer printer)
        {
            if (ReferenceEquals(Set, null))
            {
                return(true);
            }

            if (ReferenceEquals(printer, null))
            {
                return(true);
            }

            if (Set.Contains(printer))
            {
                Set.Remove(printer);
                return(true);
            }

            return(false);
        }