/usr/ is in ruby-classifier 1.3.4-2.
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/classifier.rb
/usr/lib/ruby/vendor_ruby/classifier/
/usr/lib/ruby/vendor_ruby/classifier/lsi.rb
/usr/lib/ruby/vendor_ruby/classifier/bayes.rb
/usr/lib/ruby/vendor_ruby/classifier/lsi/
/usr/lib/ruby/vendor_ruby/classifier/lsi/summary.rb
/usr/lib/ruby/vendor_ruby/classifier/lsi/content_node.rb
/usr/lib/ruby/vendor_ruby/classifier/lsi/word_list.rb
/usr/lib/ruby/vendor_ruby/classifier/extensions/
/usr/lib/ruby/vendor_ruby/classifier/extensions/string.rb
/usr/lib/ruby/vendor_ruby/classifier/extensions/vector_serialize.rb
/usr/lib/ruby/vendor_ruby/classifier/extensions/vector.rb
/usr/lib/ruby/vendor_ruby/classifier/extensions/word_hash.rb
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-classifier/
/usr/share/doc/ruby-classifier/README.Debian
/usr/share/doc/ruby-classifier/examples/
/usr/share/doc/ruby-classifier/examples/bayes.rb
/usr/share/doc/ruby-classifier/examples/summarize.rb
/usr/share/doc/ruby-classifier/copyright
/usr/share/doc/ruby-classifier/changelog.Debian.gz
/usr/share/doc/ruby-classifier/README.markdown
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/classifier-1.3.4.gemspec