code: def _stack(x, y):
      assert x.shape[1:] == y.shape[1:]
      return np.vstack((x, y))
  
imports: import functools
  import importlib
  import importlib.resources
  import re
  import warnings
  from functools import lru_cache
  import matplotlib.pyplot
  import numpy
  from numpy import newaxis
  from .rcparams import rcParams
label_desc: Use image node_id 8 for calling a global function with example usage: _stack(x, y) and returns: np