Define an interface IConvertible that indicates that the class can convert a string to C# or VB2005. The interface should have two methods: ConvertToCSharp and ConvertToVB2005. Each method should take a string, and return a string.

Implement that interface and test it by creating a class ProgramHelper that implements IConvertible. You can use simple string messages to simulate the conversion.

Extend the interface by creating a new interface, ICodeChecker. The new interface should implement one new method, CodeCheckSyntax, which takes two strings: the string to check, and the language to use. The method should return a bool. Revise the ProgramHelper class from Exercise 13-2 to use the new interface.

Demonstrate the use of is and as. Create a new class, ProgramConverter, that implements IConvertible. ProgramConverter should implement the ConvertToC-Sharp( ) and ConvertToVB( ) methods. Revise ProgramHelper so that it derives from ProgramConverter, and implements ICodeChecker.