Null checking C# with Example

Extension methods are static methods which behave like instance methods. However, unlike what happens when 
calling an instance method on a null reference, when an extension method is called with a null reference, it does 
not throw a NullReferenceException. This can be quite useful in some scenarios. 
For example, consider the following static class: 
public static class StringExtensions 
{ 
public static string EmptyIfNull(this string text) 
{ 
return text ?? String.Empty; 
} 
public static string NullIfEmpty(this string text) 
{ 
return String.Empty == text ? null : text; 
} 
} 
string nullString = null; 
string emptyString = nullString.EmptyIfNull();// will return "" 
string anotherNullString = emptyString.NullIfEmpty(); // will return null 
Live Demo on .NET Fiddle