Function select_account 

pub fn select_account(
    state: &AccountStateMap,
    pin: &OrgPin,
    org: &str,
    model: &str,
) -> Result<AccountKey, SelectionError>

Pick the account for model out of org’s walk order: the first account whose declared models include the model. Ready accounts beat saturated ones, and Bailed accounts are the last resort. A retired account - one a reload removed - is never offered.