ruby2.3-tcltk 2.3.6-2ubuntu1 (amd64 binary) in ubuntu bionic

 Ruby is the interpreted scripting language for quick and easy
 object-oriented programming. It has many features to process text
 files and to do system management tasks (as in perl). It is simple,
 straight-forward, and extensible.
 .
 This package provides Ruby/Tk, Ruby bindings for the Tk graphical user
 interface toolkit.