How to convert list to <class 'detectron2.structures.boxes.Boxes'>

[ashutoshbk]

how can convert list to detectron2.structures.boxes.Boxes format or how can convert tensor to detectron2.structures.boxes.Boxes format:
pred_boxes = (outputs['instances'].pred_boxes).__dict__['tensor'].tolist()
print(type(pred_boxes)) #ouput <class 'list'>

[ashutoshbk]

also how can we modify detectron2.structures.boxes.Boxes like append or remove etc.