code: def transformation(self, x):
      # x = self.lin(x)
      x = x @ self.weight
  
      if self.bias is not None:
          x += self.bias
      return x
  
imports: from typing import Optional
  import torch
  from torch import Tensor
  import torch.nn.functional
  from torch.nn import ModuleList, Linear, BatchNorm1d
  from torch_sparse import SparseTensor
  from torch_geometric.nn import GCNConv
  from ..models import ScalableGNN
  from torch_geometric.typing import Adj, OptTensor
label_desc: Use image node_id 4 for calling the GCNConv obj's underlying member method code with example usage: obj.transformation(x) and returns: x