def build &block
      @document += FIRST_PART
      block.call.each do |n|
        @document += n.to_s + "\n"
        @total += 1
      end
      @document += LAST_PART
    end
def build &block
      @document += FIRST_PART
      block.call.each do |n|
        @document += n.to_s + "\n"
        @total += 1
      end
      @document += LAST_PART
    end
Public: Build a document, ie build a file of bookmarks.

 block - A block that enumerate all NetscapeBookmark to put
         into the document.

 Examples

   # ary is an array of NetscapeBookmark.
   document.build do
     ary.each {|e| e }
   end

 Returns the String document.