code: def test_polyder_return_type(self):
      # Ticket #1249
      assert_(isinstance(np.polyder(np.poly1d([1]), 0), np.poly1d))
      assert_(isinstance(np.polyder([1], 0), np.ndarray))
      assert_(isinstance(np.polyder(np.poly1d([1]), 1), np.poly1d))
      assert_(isinstance(np.polyder([1], 1), np.ndarray))
  
imports: import os
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_equal, assert_array_almost_equal, assert_raises, _assert_valid_refcount
  import pytest
label_desc: Use image node_id 21 for calling the TestRegression obj's underlying member method code with example usage: obj.test_polyder_return_type() without return types