code: def forward(self, x):
      h, _ = self.backbone(x)
      out = self.out(torch.mean(h, dim=1))
      return out
  
imports: import numpy
  import torch
  from helper import index_points, square_distance, TransitionDown, TransitionUp
  from torch import nn
label_desc: Use image node_id 2 for calling the PointTransformerCLS obj's underlying member method code with example usage: obj.forward(x) and returns: out