code: def __init__(self, eps=0.2):
      super(PartSegLoss, self).__init__()
      self.eps = eps
      self.loss = nn.CrossEntropyLoss()
  
imports: import numpy
  import torch
  from helper import index_points, square_distance, TransitionDown, TransitionUp
  from torch import nn
label_desc: Use image node_id 1 to create a new PartSegLoss object from inherited base classes: nn with example: obj = PartSegLoss(eps)