Function write_list_ext 

pub fn write_list_ext<'a, S, T, I>(
    elements: I,
    write: &mut dyn Write,
    settings: &Settings,
    hints: &mut Hints,
) -> Result<(), Error>
where
    S: Integer,
    T: Parcel + 'a,
    I: IntoIterator<Item = &'a T>,

Writes a length-prefixed list to a stream.