code: def getRenderers(filename):
      
      global available_renderers
      renderers = []
      for rdrid, (renderer, module) in available_renderers.items():
          try:
              priority = renderer.canRender(filename)
          except:
              print("""Error in renderer: %s.canRender("%s"):""" % (rdrid, filename))
              traceback.print_exc()
              priority = None
          if priority:
              renderers.append((priority, rdrid))
      # sort by priority
      renderers.sort(lambda a, b: cmp(a[0], b[0]))
      # return list of IDs. Note that "none" should always be available and working
      return [a[1] for a in renderers] or ["link"]
docs: For a given DP, returns a list of renderer ids giving
      the renderers that support the source file type