using System.Collections.Generic; namespace VCommon { public static class StringExtensionMethod { public static string JoinString(this IEnumerable items, string separator = "") => string.Join(separator, items); public static bool IsNullOrEmpty(this string source) => string.IsNullOrEmpty(source); public static bool IsNullOrWhiteSpace(this string source) => string.IsNullOrWhiteSpace(source); } }