The workflow of the recipe is fairly simple, where we have a function to check whether an integer is greater than a fixed threshold or not. The UPPERLIMIT variable defines the fixed threshold for the function, which is a constant whose value will not change in the code and is accessible throughout the program.

We assigned 15 to random_number and passed it via is_big (integer value); and we then get a boolean output, either true or false, as the return type of the function is a bool type. The answer to our situation is false as 15 is not bigger than 12, which the UPPERLIMIT value set as the constant. We performed this condition checking using the if...else statement in Rust.

We cannot change the UPPERLIMIT value; when attempted, it will throw an error, which is commented in the code section.