pub fn tree(height: usize) -> Vec<String> {
    let mut tree = Vec::new();
    for i in 0..height {
        tree.push(format!(
            "{}{}{}",
            " ".repeat(height - i - 1),
            "#".repeat(i * 2 + 1),
            " ".repeat(height - i - 1)
        ));
    }
    tree
}