Binary package “gitk” in ubuntu bionic

fast, scalable, distributed revision control system (revision tree visualizer)

 Git is popular version control system designed to handle very large
 projects with speed and efficiency; it is used for many high profile
 open source projects, most notably the Linux kernel.
 .
 Git falls in the category of distributed source code management tools.
 Every Git working directory is a full-fledged repository with full
 revision tracking capabilities, not dependent on network access or a
 central server.
 .
 This package provides the gitk program, a tcl/tk revision tree visualizer.