Pine

This release improves performance for e.g. cloning, printing and many more.

The major breaking change is that node$depth has been renamed to node$height as apparantly depth caused confusing with some people for whom depth = level.

For all changes, please refer to the NEWS file, available at https://github.com/gluc/data.tree/tree/v0.1.8/NEWS

Outlook: we are working on the package documentation and count on publishing to CRAN soon. Until then, we do not expect any major API changes.