/// <summary>
/// Determine if the specified string is blank, where blank is defined 
/// as null, empty or containing only whitespace characters.
/// </summary>
/// <param name="value">string to be evaluated</param>
/// <returns>
/// true if the value is null, empty or contains only 
/// whitespace characters; otherwise false
/// </returns>
static bool IsNullOrWhiteSpace(string value)
{
    if (string.IsNullOrEmpty(value)) return true;
    return !value.Any(c => !char.IsWhiteSpace(c));
}