class_docstr: Statistic tracking the count and mean of a single :class:`torch.Tensor`.
code: def merge(self, other: "CountMeanStats") -> "CountMeanStats":
      assert isinstance(other, type(self))
      result = CountMeanStats()
      result.count = self.count + other.count
      p = self.count / max(result.count, 1)
      q = other.count / max(result.count, 1)
      result.mean = p * self.mean + q * other.mean
      return result
  
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 CountMeanStats obj's underlying member method code with example usage: obj.merge(other) and returns: result