User Defined Type Convers.
	• A conversion function allows us to define a conversion from an object of a class to another built-in type. • Conversion functions are also useful when we need to convert from an object of our class to an object of a class that we do not have access to or do not want to modify. • When we do have access to the class and are willing to modify it, we can always define a constructor taking a single argument of our class type to perform the conversion.        operator other_type();