def test_node_no_leaf():
true_node = Node('True Node')
false_node = Node('False Node')
head_node = Node('Head Node',
lambda x: x < 25,
true_child=true_node,
false_child=false_node)
assert head_node.is_leaf() == False
def test_node_leaf():
node = Node('Test Node', )
assert node.is_leaf() == True