def to_html
      html = '<table><tr>'
      @source.each{|color| html.concat("<th>" + color + "</th>")}
      html.concat("</tr><tr>")
      @source.each{|color| html.concat("<td style=\"background-color:" + color + ";\">&nbsp;</td>")}
      html += '</tr></table>'
      return html
    end
def to_html
      html = '<table><tr>'
      @source.each{|color| html.concat("<th>" + color + "</th>")}
      html.concat("</tr><tr>")
      @source.each{|color| html.concat("<td style=\"background-color:" + color + ";\">&nbsp;</td>")}
      html += '</tr></table>'
      return html
    end
display colorset on IRuby notebook as a html table
 @return [String] generated html