code: def construct_xblock_from_class(self, cls, scope_ids, field_data=None, *args, **kwargs):
          
          return self.mixologist.mix(cls)(
              runtime=self,
              field_data=field_data,
              scope_ids=scope_ids,
              *args, **kwargs
          )
docs: Construct a new xblock of type cls, mixing in the mixins
          defined for this application.