code: def start_virtual_display(self, width=1440, height=900,
                                colordepth=24, **kwargs):
          
          if self._display is None:
              logger.info("Using virtual display: '{0}x{1}x{2}'".format(
                          width, height, colordepth))
  
              self._display = Xvfb(int(width), int(height),
                                   int(colordepth), **kwargs)
              self._display.start()
              atexit.register(self._display.stop)
docs: Starts virtual display which will be
           destroyed after test execution will be end
  
          *Arguments:*
          - width: a width to be set in pixels
          - height: a height to be set in pixels
          - color_depth: a color depth to be used
          - kwargs: extra parameters
  
          *Example:*
  
          | Start Virtual Display |
          | Start Virtual Display | 1920 | 1080 |
          | Start Virtual Display | ${1920} | ${1080} | ${16} |