code: def test_sub_back_to_zero(stat):
      A = copy.deepcopy(stat)
      B = copy.deepcopy(stat)
      C = copy.deepcopy(stat)
  
      x = random.random()
      A.update(x)
      B.update(x)
  
      D = A - B
      assert math.isclose(D.get(), C.get())
  
file_path: river/river/stats/test_parallel.py
imports: from __future__ import annotations
  import copy
  import math
  import random
  import numpy
  import pytest
  from river import stats
label_desc: Use image node_id 5 for calling a global function with example usage: test_sub_back_to_zero(stat) without return types