old_contents: from neo.io.basefromrawio import BaseFromRaw
  from neo.rawio.nixrawio import NIXRawIO
  
  # This class subjects to limitations when there are multiple asymmetric blocks
  
  
  class NixIO(NIXRawIO, BaseFromRaw):
  
      name = 'NIX IO'
  
      _prefered_signal_group_mode = 'group-by-same-units'
      _prefered_units_group_mode = 'split-all'
  
      def __init__(self, filename):
          NIXRawIO.__init__(self, filename)
          BaseFromRaw.__init__(self, filename)
  
      def read_block(self, block_index=0, lazy=False, signal_group_mode=None,
                     units_group_mode=None, load_waveforms=False):
          bl = super().read_block(block_index, lazy, signal_group_mode,
                                  units_group_mode, load_waveforms)
          for chx in bl.channel_indexes:
              if "nix_name" in chx.annotations:
                  nixname = chx.annotations["nix_name"]
                  chx.annotations["nix_name"] = nixname[0]
          return bl
  
      def __enter__(self):
          return self
  
      def __exit__(self, *args):
          self.header = None
          self.file.close()
  
new_contents: from neo.io.basefromrawio import BaseFromRaw
  from neo.rawio.nixrawio import NIXRawIO
  
  # This class subjects to limitations when there are multiple asymmetric blocks
  
  
  class NixIO(NIXRawIO, BaseFromRaw):
  
      name = 'NIX IO'
  
      _prefered_signal_group_mode = 'group-by-same-units'
      _prefered_units_group_mode = 'split-all'
  
      def __init__(self, filename):
          NIXRawIO.__init__(self, filename)
          BaseFromRaw.__init__(self, filename)
  
      def read_block(self, block_index=0, lazy=False, signal_group_mode=None,
                     units_group_mode=None, load_waveforms=False):
          bl = super(NixIO, self).read_block(block_index, lazy,
                                             signal_group_mode,
                                             units_group_mode,
                                             load_waveforms)
          for chx in bl.channel_indexes:
              if "nix_name" in chx.annotations:
                  nixname = chx.annotations["nix_name"]
                  chx.annotations["nix_name"] = nixname[0]
          return bl
  
      def __enter__(self):
          return self
  
      def __exit__(self, *args):
          self.header = None
          self.file.close()
  
subject: Use Python2 compatible super() call