Vector of ints to string separated by commas

vec_csv.rs

pub fn vec_u64(original: &Vec<u64>) -> String {
    let mut list = original.clone();
    let next = list.pop();

    match next {
        Some(next) => {
            vec_u64_next(list, format!("{next}", next=next))
        },
        _ => {
            "".to_string()
        }
    }
}

fn vec_u64_next(mut list: Vec<u64>, builder: String) -> String {
    let next = list.pop();

    match next {
        Some(next) => {
            vec_u64_next(list, format!("{builder},{next}", builder=builder, next=next))
        },
        _ => {
            builder
        }
    }    
}