class_docstr: Statistic tracking only the number of samples.
  
  For example::
  
      >>> stats = CountStats()
      >>> stats.update(torch.randn(3, 3))
      >>> stats.get()
      {'count': 1}
code: def merge(self, other: "CountStats") -> "CountStats":
      assert isinstance(other, type(self))
      result = CountStats()
      result.count = self.count + other.count
      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 CountStats obj's underlying member method code with example usage: obj.merge(other) and returns: result