code: def underline
           style           = CharacterStyle.new
           style.underline = true
           if block_given?
              apply(style) {|node| yield node}
           else
              apply(style)
           end
        end
docs: This method provides a short cut means of creating an underline command
   node. The method accepts a block that will be passed a single parameter
   which will be a reference to the underline node created. After the block
   is complete the underline node is appended to the end of the child nodes
   on the object that the method is call against.