code: def forward(self, A_hat, X):
      Z_0 = Z = self.f_theta(X)
      for _ in range(self.num_hops):
          A_drop = dglsp.val_like(A_hat, self.A_dropout(A_hat.val))
          Z = (1 - self.alpha) * A_drop @ Z + self.alpha * Z_0
      return Z
  
file_path: dgl/examples/sparse/appnp.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 2 for calling the APPNP obj's underlying member method code with example usage: obj.forward(A_hat, X) and returns: Z