Function concordium_std::serial_set_no_length

pub fn serial_set_no_length<'a, W, K>(
    map: &BTreeSet<K>, 
    out: &mut W
) -> Result<(), <W as Write>::Err> where
    K: 'a + Serial,
    W: Write, 

Write a BTreeSet as an ascending list of keys, without the length information.