code: def test_external_mean_axis(self, xp, dtype):
      a = testing.shaped_arange((2, 3, 4), xp, dtype)
      return xp.mean(a, axis=1)
  
imports: import math
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 4 for calling the TestMeanVar obj's underlying member method code with example usage: obj.test_external_mean_axis(xp, dtype) and returns: xp