>> require "hpricot" => true >> doc = Hpricot('') {} => #<Hpricot::Doc> >> doc.doctype('HTML', 'hoge') ArgumentError: wrong number of arguments (2 for 3) from (irb):3:in `doctype' from (irb):3 >> doc.doctype('HTML', 'hoge', '') /usr/local/ruby-1.8.7/lib</hpricot::doc>…