    # File lib/facets/more/tagiterator.rb, line 176
      def nth(tag,n,closetag=nil)
        raise RuntimeError,"nth: number not specified" unless n
        t=0
        e=s=0   # for their scope
        d=nil

        1.upto(n) do |i|
          s,d = find_opentag(tag,t)
          raise RuntimeError,"tag(#{tag}) not found at(#{i})" unless s

          if closetag then
            e=find_closetag(closetag,s,tag)
          else
            e=find_closetag(tag,s)
          end
          e=-1 unless e
          t=@text.index('>',e+1)
          t=@text.length unless t
        end
        yield self.class.new(text[s..e],tag,parse_attribute(d))
        self.class.new(text[t+1..-1])
      end