old_contents: from polypy.base import x
  
  
  def test_call():
      f = 2 * x
      assert f(2) == 4
  
      f = 3 * x ** 2
      assert f(3) == 27
  
  
  def test_str():
      f = 2 * x
      assert str(f) == "2x"
  
      f = x * 2
      assert str(f) == "2x"
  
  
  def test_square():
      f = x
      assert f * x == x ** 2
  
      f = 3 * x
      assert f ** 2 == 9 * x ** 2
  
  
  def test_multiply_x_and_linear_term():
      f = 2 * x
      assert f * x == (2 * x ** 2)
  
  
  def test_multiply_two_linear_terms():
      assert (3 * x) * (2 * x) == 6 * x ** 2
  
new_contents: from polypy.base import x
  
  
  def test_call():
      f = 2 * x
      assert f(2) == 4
  
      f = 3 * x ** 2
      assert f(3) == 27
  
  
  def test_str():
      f = 2 * x
      assert str(f) == "2x"
  
      f = x * 2
      assert str(f) == "2x"
  
  
  def test_square():
      f = x
      assert f * x == x ** 2
  
      f = 3 * x
      assert f ** 2 == 9 * x ** 2
  
  
  def test_multiply_x_and_linear_term():
      f = 2 * x
      assert f * x == (2 * x ** 2)
  
  
  def test_multiply_two_linear_terms():
      assert (3 * x) * (2 * x) == 6 * x ** 2
  
  
  def test_multiply_two_linear_expressions():
      assert str((x + 1) * (x + 2)) == "x^2 + 2x + x + 2"
  
subject: Add test for multiplying linear terms