Function hashjoin::measurement::data_point::serialize_vec

fn serialize_vec<S, T>(
    option: &Option<Vec<T>>, 
    ser: S
) -> Result<S::Ok, S::Error> where
    S: Serializer,
    T: ToString, 

Serialize Option<Vec<T>> by converting it into a String.

This is necessary because the csv crate does not support nesting Vec instead of flattening it.