A float can hold any number, which is exactly the problem. Primitive obsession is why the same validation keeps reappearing, and value objects are the fix.

A pure function returns the same output for the same input and touches nothing else. That single property is what makes code predictable and trivial to test.

Deeply nested if/else blocks are hard to read and easy to break. Guard clauses flatten your logic with early returns so the happy path stays obvious.