code: def test_stack_out(self, xp, dtype):
      a = testing.shaped_arange((3, 4), xp, dtype)
      b = testing.shaped_reverse_arange((3, 4), xp, dtype)
      c = testing.shaped_arange((3, 4), xp, dtype)
      out = xp.zeros((3, 3, 4), dtype=dtype)
      xp.stack((a, b, c), axis=1, out=out)
      return out
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy import cuda
label_desc: Use image node_id 54 for calling the TestJoin obj's underlying member method code with example usage: obj.test_stack_out(xp, dtype) and returns: out