code: def conv(self, x, pos, edge_index, batch):
      return self._conv.forward(x, pos, edge_index)
  
imports: from math import ceil
  import torch
  from torch.nn import Sequential, Linear, BatchNorm1d
  from torch.nn import ELU, Conv1d
  from torch_geometric.nn import Reshape
  from torch_geometric.nn.inits import reset
  from torch_points3d.core.spatial_ops import RandomSampler, FPSSampler, DilatedKNNNeighbourFinder
  from torch_points3d.core.base_conv.message_passing import *
label_desc: Use image node_id 2 for calling the PointCNNConvDown obj's underlying member method code with example usage: obj.conv(x, pos, edge_index, batch) and returns: self