rubocop binary package in Ubuntu Focal amd64

 rubocop is a static code analyzer for Ruby, out of the box it will
 enforce many of the guidelines outlined in the community Ruby Style Guide.
 .
 Most aspects of its behavior can be tweaked via various configuration
 options.
 .
 Apart from reporting problems in your code, RuboCop can also
 automatically fix some of the problems for you.

Source package