code: def test_dstack_single_element(self, xp):
      a = testing.shaped_arange((1, 2, 3), xp)
      return xp.dstack((a,))
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy import cuda
label_desc: Use image node_id 30 for calling the TestJoin obj's underlying member method code with example usage: obj.test_dstack_single_element(xp) and returns: xp