gem install asciidoctor NOKOGIRI_USE_SYSTEM_LIBRARIES=1 gem install asciidoctor-epub3 --pre gem install pygments.rb
gem install asciidoctor-pdf --pre gem install rouge
asciidoctor-epub3 -D output sample-book.adoc
asciidoctor -b html5 -d book -D output sample-book.adoc
asciidoctor-pdf -D output sample-book.adoc