def create_leaf_list(root):
    """
    Question 10.12: Create list from leaves
    of binary tree
    """
    if root.left is None and root.right is None:
        return [root.val]

    ls = []
    if root.left is not None:
        ls.extend(create_leaf_list(root.left))
    if root.right is not None:
        ls.extend(create_leaf_list(root.right))
    return ls