code: def test_lstsq_empty_matrix(self, xp, dtype, i, j, k, rcond):
      a = xp.empty((i, j), dtype)
      assert a.size == 0
      b_shape = (i,) if k is None else (i, k)
      b = testing.shaped_random(b_shape, xp, dtype)
      return xp.linalg.lstsq(a, b, rcond)
  
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy.testing import _condition
  import cupyx
  from cupy.cublas import get_batched_gesv_limit, set_batched_gesv_limit
label_desc: Use image node_id 4 for calling the TestLstsq obj's underlying member method code with example usage: obj.test_lstsq_empty_matrix(xp, dtype, i, j, k, rcond) and returns: xp