code: def test_polymulx(self):
      assert_equal(poly.polymulx([0]), [0])
      assert_equal(poly.polymulx([1]), [0, 1])
      for i in range(1, 5):
          ser = [0] * i + [1]
          tgt = [0] * (i + 1) + [1]
          assert_equal(poly.polymulx(ser), tgt)
  
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 TestArithmetic obj's underlying member method code with example usage: obj.test_polymulx() without return types