Function unmatched 

pub async fn unmatched(
    config: &Config,
    admin: Option<&str>,
    period: Option<&str>,
    bank_account: &str,
    format: Option<&str>,
    quiet: bool,
) -> Result<(), YukiError>

Find bank transactions on a given GL account that have no matching invoice.

Each bank debit (negative amount) is first matched by absolute amount against outstanding creditor items. Any remaining unmatched debits are then checked against booked invoices in the archive for the same period. Only transactions that match neither source are reported.