public override CPDLPos GetCPDL()
        {
            CPDLString stringChoice = new CPDLString(this.str);

            return(new CPDLFirstOrLastOccPos(stringChoice));
        }
        public override CPDLSet GetCPDL()
        {
            CPDLString stringChoice = new CPDLString(this.str);

            return(new CPDLIndOfSet(stringChoice));
        }