class_docstr: Class implementing the Tree Traversal strategy in PyTorch.
code: def aggregation(self, x):
      output = x.view(
          -1, self.n_gbdt_classes, self.n_trees_per_class
      ).sum(2)
  
      return self.post_transform(output)
  
imports: from abc import abstractmethod
  from enum import Enum
  import numpy
  import torch
  from .None import constants
  from ._physical_operator import PhysicalOperator
  from .None import _tree_commons
label_desc: Use image node_id 2 for calling the TreeTraversalGBDTImpl obj's underlying member method code with example usage: obj.aggregation(x) and returns: self