text: from .find_maximum_value_binary_tree import find_maximum_value
  from .bst import BST
  
  
  def test_find_maximum_value_balanced(balanced_bst):
      """Test find max value in balanced tree."""
      assert find_maximum_value(balanced_bst) == 20
  
  
  def test_find_maximum_value_left(left_heavy):
      """Test find max value in left-heavy tree."""
      assert find_maximum_value(left_heavy) == 10
  
  
  def test_find_maximum_value_right(right_heavy):
      """Test find max value in right-heavy tree."""
      assert find_maximum_value(right_heavy) == 9
  