Ruby refactoring exercise

gistfile1.rb

class Array
  def to_annotated_xml(root)
    output = "<#{root}>"

    each do |i|
      if i.is_a?(Fixnum)
        output << "<number>#{i}</number>"
      elsif i.is_a?(String)
        if i.match(/@/)
          output << "<email>#{i}</email>"
        else
          output << "<string>#{i}</string>"
        end
      else
        output << "<value>#{i}</value>"
      end
    end

    output << "</#{root}>"
  end
end

p [1, "Stephen", "stephenb@reallyenglish.com"].to_annotated_xml("person")