code: def test_hstack_scalars(self, xp):
      a = testing.shaped_arange((), xp)
      b = testing.shaped_arange((), xp)
      c = testing.shaped_arange((), xp)
      return xp.hstack((a, b, c))
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy import cuda
label_desc: Use image node_id 34 for calling the TestJoin obj's underlying member method code with example usage: obj.test_hstack_scalars(xp) and returns: xp