code: def add_members(current):
      
      newly_added, existing = [], []
      read_only = current.input['read_only']
      for member_key in current.input['members']:
          sb, new = Subscriber(current).objects.get_or_create(user_id=member_key,
                                                              read_only=read_only,
                                                              channel_id=current.input['channel_key'])
          if new:
              newly_added.append(member_key)
          else:
              existing.append(member_key)
  
      current.output = {
          'existing': existing,
          'newly_added': newly_added,
          'status': 'OK',
          'code': 201
      }
docs: Subscribe member(s) to a channel
  
          .. code-block:: python
  
              #  request:
                  {
                  'view':'_zops_add_members',
                  'channel_key': key,
                  'read_only': boolean, # true if this is a Broadcast channel,
                                        # false if it's a normal chat room
                  'members': [key, key],
                  }
  
              #  response:
                  {
                  'existing': [key,], # existing members
                  'newly_added': [key,], # newly added members
                  'status': 'Created',
                  'code': 201
                  }