code: def forward(self, e, i, num_nodes):
      _, e2 = e
      v = scatter(e2, i, dim=0, dim_size=num_nodes)
      v = self.lin_up(v)
      for lin in self.lins:
          v = self.act(lin(v))
      v = self.lin(v)
      v = scatter(v[i], i, dim=0, dim_size=num_nodes, reduce="mean")
      return v
  
imports: import torch
  from torch import nn
  from torch.nn import Linear, Embedding
  from torch_geometric.nn.inits import glorot_orthogonal
  from torch_geometric.nn import radius_graph
  from torch_scatter import scatter
  import torch.nn.functional
  from math import sqrt
  from .geometric_computing import xyztodat
  from .features import dist_emb, angle_emb, torsion_emb
label_desc: Use image node_id 3 for calling the update_v obj's underlying member method code with example usage: obj.forward(e, i, num_nodes) and returns: v