Function simple_ml::std_dev

pub fn std_dev<T>(list1: &Vec<T>) -> f64 where
    T: Sum<T> + Div<Output = T> + Debug + Display + Add + Copy + Add<T, Output = T> + Sub<T, Output = T> + Mul<T, Output = T> + ToString + FromStr,
    <T as FromStr>::Err: Debug,