public static string GetVpiVci(FacilityDataRetrievalArgument args)
        {
            var assignment = args.GetPairAssignment();

            switch (args.GetFacilityType())
            {
                case FacilityType.CopperFacility: return string.Format("{0}/{1}", assignment.VPI, assignment.VCI);
                case FacilityType.FiberFacility:
                {
                    var portAssignment = new OntPortAssignmentsDto().Assignment;
                    if (args.GetFiberPlantData().OntPortAssignments != null)
                    {
                        portAssignment = (args.GetFiberPlantData().OntPortAssignments.FirstOrDefault()
                                           ?? new OntPortAssignmentsDto()).Assignment;
                    }
                    return GetUnderscoreSeparatedValueByIndex(portAssignment, 1);
                }
                default: return string.Empty;
            }
        }
        public static string GetOntUnitAddress(FacilityDataRetrievalArgument args)
        {
            var assignment = new OntPortAssignmentsDto().Assignment;
            if (args.GetFiberPlantData().OntPortAssignments != null)
            {
                assignment = (args.GetFiberPlantData().OntPortAssignments.FirstOrDefault() ?? new OntPortAssignmentsDto()).Assignment;
            }

            return GetUnderscoreSeparatedValueByIndex(assignment, 0);
        }