def insert(text, offset)
         if !@text.nil?
            @text = @text[0, offset] + text.to_s + @text[offset, @text.length]
         else
            @text = text.to_s
         end
      end
def insert(text, offset)
         if !@text.nil?
            @text = @text[0, offset] + text.to_s + @text[offset, @text.length]
         else
            @text = text.to_s
         end
      end
This method inserts a String into the existing text within a TextNode
 object. If the TextNode contains no text then it is simply set to the
 text passed in. If the offset specified is past the end of the nodes
 text then it is simply appended to the end.

 ==== Parameters
 text::    A String containing the text to be added.
 offset::  The numbers of characters from the first character to insert
           the new text at.