code: def backward(self):
      self.loss_seg.backward()
  
file_path: torch-points3d/torch_points3d/models/segmentation/minkowski.py
imports: import logging
  import torch.nn.functional
  import torch
  from torch_points3d.modules.MinkowskiEngine import *
  from torch_points3d.models.base_architectures import UnwrappedUnetBasedModel
  from torch_points3d.models.base_model import BaseModel
  from torch_points3d.datasets.segmentation import IGNORE_LABEL
  from torch_points3d.applications.minkowski import Minkowski
label_desc: Use image node_id 4 for calling the Minkowski_Baseline_Model obj's underlying member method code with example usage: obj.backward() without return types