/usr/ is in ruby-ast 2.3.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/ast/
/usr/lib/ruby/vendor_ruby/ast/node.rb
/usr/lib/ruby/vendor_ruby/ast/processor/
/usr/lib/ruby/vendor_ruby/ast/processor/mixin.rb
/usr/lib/ruby/vendor_ruby/ast/processor.rb
/usr/lib/ruby/vendor_ruby/ast/sexp.rb
/usr/lib/ruby/vendor_ruby/ast.rb
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-ast/
/usr/share/doc/ruby-ast/README.YARD.md
/usr/share/doc/ruby-ast/README.md
/usr/share/doc/ruby-ast/changelog.Debian.gz
/usr/share/doc/ruby-ast/copyright
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/ast-2.3.0.gemspec