Computer code certainly shouldn't be at the beginning of the Rules section. If it clarifies the rules in a way that is important, it might be okay to include it in the Notes section with some text describing what it illustrates or in the Rules section with a <DETAILS> tag. However, you should be able to describe the rules without referring to code, and for readers who are not programmers, it is best that you do so. You shouldn't really include code unless there is some overriding reason to do so.
Computer code certainly shouldn't be at the beginning of the Rules section. If it clarifies the rules in a way that is important, it might be okay to include it in the Notes section with some text describing what it illustrates or in the Rules section with a
<DETAILS>tag. However, you should be able to describe the rules without referring to code, and for readers who are not programmers, it is best that you do so. You shouldn't really include code unless there is some overriding reason to do so.