Chain of Resp. : A way of passing a request between a chain of objects.
Avoid coupling the sender of a request to its receiver by giving more
than one object a chance to handle the request. Chain the receiving
objects and pass the request along the chain until an object handles it.
In each concrete handler, You need to 1) judge if you should handle(),
2) set next successor.
Just like composite, but it only include one successor.
How to judge if I handle a request or pass it to the success, you can
hard code it or make a request class.
