code: def set_swimlane(self, value):
          
          if self.multiselect:
              value = value or []
              children = []
  
              for child in value:
                  children.append(self.cast_to_python(child))
  
              return self._set(children)
  
          return super(MultiSelectField, self).set_swimlane(value)
docs: Cast all multi-select elements to correct internal type like single-select mode