code: def test_polyvander3d(self):
      # also tests polyval3d for non-square coefficient array
      x1, x2, x3 = self.x
      c = np.random.random((2, 3, 4))
      van = poly.polyvander3d(x1, x2, x3, [1, 2, 3])
      tgt = poly.polyval3d(x1, x2, x3, c)
      res = np.dot(van, c.flat)
      assert_almost_equal(res, tgt)
  
      # check shape
      van = poly.polyvander3d([x1], [x2], [x3], [1, 2, 3])
      assert_(van.shape == (1, 5, 24))
  
imports: from functools import reduce
  from fractions import Fraction
  import numpy
  import numpy.polynomial.polynomial
  import pickle
  from copy import deepcopy
  from numpy.testing import assert_almost_equal, assert_raises, assert_equal, assert_, assert_array_equal, assert_raises_regex
label_desc: Use image node_id 3 for calling the TestVander obj's underlying member method code with example usage: obj.test_polyvander3d() without return types