public void hspan(double start,double end,Paint color,String legend){
  LegendText legendText=new LegendText(color,legend);
  comments.add(legendText);
  plotElements.add(new HSpan(start,end,color,legendText));
}

public void hspan ( double start , double end , Paint color , String legend ) { LegendText legendText = new LegendText ( color , legend ) ; comments . add ( legendText ) ; plotElements . add ( new HSpan ( start , end , color , legendText ) ) ; }
draws a horizontal span into the graph and optionally adds a legend .
