Function refit_all 

fn refit_all(
    language: &FastText,
    rows: &Rows<'_>,
    order: &[usize],
    test_ids: &[usize],
    test_words: &[Vec<String>],
    c: f64,
    options: &Options,
    cancel: &Cancel,
    step: &mut dyn FnMut(&str),
) -> Result<(Table, Refit), LearnError>

The model learned again, cost c, from every message (order, time order), the newest included: standardized anew, Platt on forward folds over all of it, folded; the fold tested on the test messages. The table to write (its metadata counts what it learned from; its metrics are the caller’s), and what to say of it.