Date is still messy. But I will take care of it.

For my reference:

create a new `case class LedgerExportData(date:String, Seq[LedgerExportEntry])`

Let `ledgerExport` return a `Seq[LedgerExportData]`

If there are no transactions, just return a Nil

Else return Seq(LedgerExportData(date, entries))