class_docstr: Abstract base class for streamable statistics of trees of tensors.
  
  Derived classes must implelement :meth:`update`, :meth:`merge`, and
  :meth:`get`.
docstr: Return the aggregate statistic.
docstr_tok: ["Return","the","aggregate","statistic","."]
code: def get(self) -> Any:
      """
      Return the aggregate statistic.
      """
      raise NotImplementedError
  
imports: import copy
  from abc import ABC, abstractmethod
  from collections import defaultdict
  from typing import Any, Callable, Dict, Hashable, Union
  import torch
  from pyro.ops.welford import WelfordCovariance
label_desc: Use image node_id 3 for calling the StreamingStats obj's underlying member method code with example usage: obj.get() without return types