code: def forward(self, v, dist, dist_emb, edge_index):
      j, _ = edge_index
      C = 0.5 * (torch.cos(dist * PI / self.cutoff) + 1.0)
      W = self.mlp(dist_emb) * C.view(-1, 1)
      v = self.lin(v)
      e = v[j] * W
      return e
  
imports: from math import pi
  import torch
  import torch.nn.functional
  from torch.nn import Embedding, Sequential, Linear
  from torch_scatter import scatter
  from torch_geometric.nn import radius_graph
label_desc: Use image node_id 3 for calling the update_e obj's underlying member method code with example usage: obj.forward(v, dist, dist_emb, edge_index) and returns: e