code: def colour(fore, back)
           style            = CharacterStyle.new
           style.foreground = fore
           style.background = back
           root.colours << fore
           root.colours << back
           if block_given?
              apply(style) {|node| yield node}
           else
              apply(style)
           end
        end
docs: This method provides a short cut menas of creating a colour node that
   deals with foreground and background colours. The method accepts a
   block that will be passed a single parameter which will be a reference
   to the colour node created. After the block is complete the colour node
   is append to the end of the child nodes on the object that the method
   is called against.
  
   ==== Parameters
   fore::  The foreground colour to be applied by the command.
   back::  The background colour to be applied by the command.