pub fn rewrite_morph<'a>(

    mut model: Model,

    rule_sets: &Vec<&'a RuleSet<'a>>,

    prop_multiple_equally_applicable: bool,

) -> Model {

    let submodel = model.as_submodel_mut();

    let rules_grouped = get_rules_grouped(rule_sets)

        .into_iter()

        .map(|(_, rule)| rule.into_iter().map(|f| f.rule).collect_vec())

        .collect_vec();

    let selector = if prop_multiple_equally_applicable {

        select_panic

    } else {

        select_first

    };

    let engine = EngineBuilder::new()

        .set_selector(selector)

        .append_rule_groups(rules_grouped)

        .build();

    let (expr, symbol_table) = engine.morph(submodel.root().clone(), submodel.symbols().clone());

    *submodel.symbols_mut() = symbol_table;

    submodel.replace_root(expr);

    model

}