using System.Collections.Generic;
public enum InvoiceIssue {
public static void Main()
List<InvoiceIssue> invoiceIssues = new List<InvoiceIssue> { InvoiceIssue.NotAnInvoice, InvoiceIssue.PageMissing };
Console.WriteLine(string.Join(",", invoiceIssues));
invoiceIssues = new List<InvoiceIssue> {};
Console.WriteLine(string.Join(",", invoiceIssues));
invoiceIssues = new List<InvoiceIssue> { InvoiceIssue.PageOutOfOrder };
Console.WriteLine(string.Join(",", invoiceIssues));