<em>Prototype:</em> It is an early sample, model, or release of a product built by the programmer to test a concept or process and that will how the final product will look like.
The correct word for the blank space is: prototype.
Explanation:
In computer science, a prototype is built to test if theoretical propositions can be translated into factual systems. The prototype is the draft of what the final software could give and include core features only. Designing prototypes is an opportunity for the programmers because the basic layout could spot unexpected failures that could or could not be corrected.
