code: def get_callbacks(service):
      
      callbacks = list(getattr(settings, 'MAMA_CAS_ATTRIBUTE_CALLBACKS', []))
      if callbacks:
          warnings.warn(
              'The MAMA_CAS_ATTRIBUTE_CALLBACKS setting is deprecated. Service callbacks '
              'should be configured using MAMA_CAS_SERVICES.', DeprecationWarning)
  
      for backend in _get_backends():
          try:
              callbacks.extend(backend.get_callbacks(service))
          except AttributeError:
              raise NotImplementedError("%s.%s.get_callbacks() not implemented" % (
                  backend.__class__.__module__, backend.__class__.__name__)
              )
      return callbacks
docs: Get configured callbacks list for a given service identifier.