code: def test_vander(self, xp, dtype):
      a = testing.shaped_arange((3,), xp, dtype=dtype)
      return xp.vander(a, N=self.N, increasing=self.increasing)
  
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 1 for calling the TestVander obj's underlying member method code with example usage: obj.test_vander(xp, dtype) and returns: xp