title: How to dynamically modifying the PlotLine in Highcharts
body: <p>Is there any way to dynamically modifying the PlotLine in Highcharts or Highstock?</p>
  
  <p>I found there are both <a href="http://api.highcharts.com/highstock#Axis.addPlotLine%28%29">addPlotLine</a> and removePlotLine in api. I don't want to delete the Plotline but just want to have a change.</p>