Function argle::arg_opt_by

pub fn arg_opt_by<T, E, F>(
    short: &str, 
    long: &str, 
    doc: &str, 
    hint: &str, 
    parse: F
) -> impl Param<Item = Option<T>> where
    E: Clone + Debug + Display,
    F: Fn(String) -> Result<T, E>,