code: def get_channel_classes(channel_code):
          
          if channel_code:
              # Channel code is case-insensitive
              channel_code = channel_code.upper()
  
              if channel_code not in INTEGRATED_CHANNEL_CHOICES:
                  raise CommandError(_('Invalid integrated channel: {channel}').format(channel=channel_code))
  
              channel_classes = [INTEGRATED_CHANNEL_CHOICES[channel_code]]
          else:
              channel_classes = INTEGRATED_CHANNEL_CHOICES.values()
  
          return channel_classes
docs: Assemble a list of integrated channel classes to transmit to.
  
          If a valid channel type was provided, use it.
  
          Otherwise, use all the available channel types.