code: def i2s_frameid(x):
      
      try:
          return PNIO_FRAME_IDS[x]
      except KeyError:
          pass
      if 0x0100 <= x < 0x1000:
          return "RT_CLASS_3 (%4x)" % x
      if 0x8000 <= x < 0xC000:
          return "RT_CLASS_1 (%4x)" % x
      if 0xC000 <= x < 0xFC00:
          return "RT_CLASS_UDP (%4x)" % x
      if 0xFF80 <= x < 0xFF90:
          return "FragmentationFrameID (%4x)" % x
      return x
docs: Get representation name of a pnio frame ID
  
      :param x: a key of the PNIO_FRAME_IDS dictionary
      :returns: str