use serde_derive::{Serialize, Deserialize}; // 1.0.101
use serde_json; // 1.0.40

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
#[serde(untagged)]
pub enum Aud {
    One(String),
    Many(Vec<String>),
}
fn main() {
    let foo = Aud::One ("CBr3zBlrKBbwmxOAM1avZQ==".into());
    let bar = Aud::Many (vec![ "1".into(), "2".into() ]);
    let foo_s = serde_json::to_string (&foo).unwrap();
    let bar_s = serde_json::to_string (&bar).unwrap();
    println!("{} - {}", foo_s, foo_s.len());
    println!("{} - {}", bar_s, bar_s.len());
}