code: def _list_devices(self, df_output):
          
          all_devices = [l.strip().split() for l in df_output.splitlines()]
  
          # Skip the header row and empty lines.
          raw_devices = [l for l in all_devices[1:] if l]
  
          # Flatten the disks that appear in the mulitple lines.
          flattened_devices = self._flatten_devices(raw_devices)
  
          # Filter fake or unwanteddisks.
          return [d for d in flattened_devices if self._keep_device(d)]
docs: Given raw output for the df command, transform it into a normalized
          list devices. A 'device' is a list with fields corresponding to the
          output of df output on each platform.