def add_text( text )
      if text.kind_of? String 
        if @children[-1].kind_of? Text
          @children[-1] << text
          return
        end
        text = Text.new( text, whitespace(), nil, raw() )
      end
      self << text unless text.nil?
      return self
    end
def add_text( text )
      if text.kind_of? String 
        if @children[-1].kind_of? Text
          @children[-1] << text
          return
        end
        text = Text.new( text, whitespace(), nil, raw() )
      end
      self << text unless text.nil?
      return self
    end
A helper method to add a Text child.  Actual Text instances can
 be added with regular Parent methods, such as add() and <<()
 text::
   if a String, a new Text instance is created and added
   to the parent.  If Text, the object is added directly.
 Returns:: this Element
  e = Element.new('a')          #-> <e/>
  e.add_text 'foo'              #-> <e>foo</e>
  e.add_text Text.new(' bar')    #-> <e>foo bar</e>
 Note that at the end of this example, the branch has <b>3</b> nodes; the 'e'
 element and <b>2</b> Text node children.