Having fun with C# 3.0 extensions

namespace ExtensionExampleApp.Utility
{
    public static class Extensions
    {
        /// <summary>
        /// Checks if string is null, empty or consists only of spaces (in which case returns false)
        /// </summary>
        /// <param name="value"></param>
        /// <returns>true if string is none of the above</returns>
        public static bool HasValue(this string text)
        {
            return (text != null && text.Trim() != string.Empty);        
        }


        public static string AddExclamationMark(this string text)
        {
            return text + "!";
        }

        public static string AddAditionalText(this string text, string add)
        {
            return text + add;
        }
    }

    public static class StringHelper
    {
        //static method for C# 2.0
        //identical to Exentensions.HasValue except for the keyword 'this'
        public static bool HasValue(string text)
        {
            return (text != null && text.Trim() != string.Empty);
        }
    }
}