code: def find_channel_groups(chan):
      
      labels = chan.return_label()
      group_names = {match('([A-Za-z ]+)\d+', label).group(1) for label in labels}
  
      groups = {}
      for group_name in group_names:
          groups[group_name] = [label for label in labels if label.startswith(group_name)]
  
      return groups
docs: Channels are often organized in groups (different grids / strips or
      channels in different brain locations), so we use a simple heuristic to
      get these channel groups.
  
      Parameters
      ----------
      chan : instance of Channels
          channels to group
  
      Returns
      -------
      groups : dict
          channel groups: key is the common string, and the item is a list of
          labels