elpa-xr binary package in Ubuntu Lunar amd64

 XR converts Emacs regular expressions to the structured rx form, thus
 being an inverse of rx. It can also find mistakes and questionable
 constructs inside regexp strings.
 .
 It can be useful for:
 .
   * Migrating existing code to rx form
   * Understanding what a regexp string really means
   * Finding errors in regexp strings
 .
 It can also parse and find mistakes in skip-sets, the regexp-like
 arguments to skip-chars-forward and skip-chars-backward.

Source package