We have two copies of RecursiveDataStructureTraverser, one in https://github.com/wp-cli/entity-command/ and one in https://github.com/wp-cli/cache-command/.

Ideally, we'd just have one copy of the class. It could live in this repository, or it could live as a standalone package.

From wp-cli/cache-command#89

Done is:

• We only have one copy of the class, and it's referenced by each repository.