code: def compute_loss(self, y_pred, y_true):
      return self.loss_fn(y_pred, y_true.long())
  
imports: import torch
  import numpy
  from scipy.special import softmax
  from pytorch_tabnet.utils import SparsePredictDataset, PredictDataset, filter_weights
  from pytorch_tabnet.abstract_model import TabModel
  from pytorch_tabnet.multiclass_utils import infer_output_dim, check_output_dim
  from torch.utils.data import DataLoader
  import scipy
label_desc: Use image node_id 4 for calling the TabNetClassifier obj's underlying member method code with example usage: obj.compute_loss(y_pred, y_true) and returns: self