Convert String to Option<f64>

main.rs

fn main() {
    let test: String = "0.123".into();
        let out = test.parse::<f64>().ok(); // parse test into Some(0.123) here
    // my failed attempt:
    // time_index: Some(fields[3].parse::<f64>().unwrap_or_default()),
    let out = test.parse::<f64>().ok(); // parse test into Some(0.123) here
    assert_eq!(out, Some(0.123));
}