Code Review for a sales tax problem solved using Elixir

Thanks to your wonderful suggestions @david_ex I’ve been able to gain valuable insights on how do I write better typespecs with regard to my code. I’ve attempted to add all possible changes in this PR based on the discussions that we’ve had through some of the earlier threads on this post.

If you think that there’s still scope for any further improvement to the updated version of how I’ve used typespecs, please do let me know.

Thank you for sharing your experience of how one could use typespecs more efficiently :slight_smile: