code: def view(self, tempname='/tmp/tempimage'):
          
          import os
          # Test if casaviewer can be found.
          # On OS-X 'which' always returns 0, so use test on top of it.
          if os.system('test -x `which casaviewer` > /dev/null 2>&1') == 0:
              six.print_("Starting casaviewer in the background ...")
              self.unlock()
              if self.ispersistent():
                  os.system('casaviewer ' + self.name() + ' &')
              elif len(tempname) > 0:
                  six.print_("  making a persistent copy in " + tempname)
                  six.print_("  which should be deleted after the viewer has ended")
                  self.saveas(tempname)
                  os.system('casaviewer ' + tempname + ' &')
              else:
                  six.print_("Cannot view because the image is in memory only.")
                  six.print_("You can browse a persistent copy of the image like:")
                  six.print_("   t.view('/tmp/tempimage')")
          else:
              six.print_("casaviewer cannot be found")
docs: Display the image using casaviewer.
  
          If the image is not persistent, a copy will be made that the user
          has to delete once viewing has finished. The name of the copy can be
          given in argument `tempname`. Default is '/tmp/tempimage'.