code: def test_poly1d(self):
      # Ticket #28
      assert_equal(
          np.poly1d([1]) - np.poly1d([1, 0]), np.poly1d([-1, 1])
      )
  
imports: import os
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_equal, assert_array_almost_equal, assert_raises, _assert_valid_refcount
label_desc: Use image node_id 1 for calling the TestRegression obj's underlying member method code with example usage: obj.test_poly1d() without return types