Generify with compiler errors - Starting function

main.rs

fn sum(numbers: &[i32]) -> i32 {
    let mut total = numbers[0];
    for i in numbers.into_iter().skip(1) {
        total += *i;
    }
    total
}

fn main() {
    let numbers = vec![23, -4, 3, 10];
    let sum = sum(&numbers);
    assert_eq!(sum, 32);
}