How to predict the repeated response of the client by his examples of communication with the server?

Question

Computer networks

The man is a master at this. Let's take an example of communication between the client and the server.
The server returns the string

{ response: [555,333] }

The client sends a request:

First=555&Last=333;

The server returns a string

{ response: [Hhh,Ddd] }

The client sends a request:

First=Hhh&Last=Ddd;

The server returns a string

{ response: [1,2} }

According to the previous examples, the program should return the client's response. Here's one:

First=1&Last=2;

I think very often in the life of a programmer one has to find such simple dependencies. For example, for an http parser. The site sets cookies and the client must remember and reproduce them. And so every time at registration.
Would like to know if anyone has done this. After all, the thing is very useful and can save a lot of time.