Exercise 9: clippy warns against unused enum field when it is only used in debug derivation.

[Yehuda-blip]

Another fantastic exercise, I love this book!

Clippy will warn against unused code (the numeric fields of the NumberType enum), even though they are printed in the show function.

warning: field `0` is never read
  --> exercises/09_ambiguity_and_ordering/main.rs:10:20
   |
10 |     PositiveNumber(u32),
   |     -------------- ^^^
   |     |
   |     field in this variant
   |
   = note: `NumberType` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
   = note: `#[warn(dead_code)]` on by default
help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
   |
10 |     PositiveNumber(()),
   |                    ~~

I simply put a #[allow(dead_code)] annotation over NumberType to solve this issue.