code: def smooth(A_hat, label, soft_label, mask):
      soft_label[mask] = label[mask].float()
      return label_propagation(A_hat, soft_label)
  
file_path: dgl/examples/sparse/c_and_s.py
imports: import dgl.sparse
  import torch
  import torch.nn
  import torch.nn.functional
  from dgl.data import CoraGraphDataset
  from torch.optim import Adam
label_desc: Use image node_id 3 for calling a global function with example usage: smooth(A_hat, label, soft_label, mask) and returns: label_propagation