Function learn_and_write 

pub fn learn_and_write(
    ballots: &[(String, String)],
    outcome: &str,
    beta: f64,
    about: &[String],
) -> Result<(Vec<Trust>, Vec<Persona>)>

learn_about and learn_anchors together, written to the pack: the rows, then the personas the outcome moved. Returns what was written.

Errors

The pack refusing a row or a persona.