Calculate order shipping cost (multi-part implementation with tests)

Calculate Order Shipping Cost (multi-part implementation + write your own tests) Given an order and its shipping/delivery information, implement a function that calculates the shipping cost. The task is split into 3 parts, progressively adding rules/features. For parts 2 and 3, you are expected to write your own test cases to validate the implementation. Note: The shared experience does not include the full business rules, exact I/O format, or the detailed requirements of each part, so this is kept as a high-level summary only.