title: How to format the YvalueAxis labels in python reportlab
body: <p>I'm creating a VerticalBarChart with python ReportLab. </p>
  
  <p>The values on the Y axis are times as timedelta (HH:MM:SS). I had to convert this values to seconds to be able to draw the chart. So I get the second values on the Y axis.</p>
  
  <p>How can I format this labels according to the HH:MM:SS format??</p>
  
  <p>If this is not possible, how could I hide this labels?</p>