in src/main/scala/InvoiceHelper.scala [7:13]
def invoicesToProcess(accountId: String): String \/ List[Invoice] = {
logInfo(accountId, "collecting invoice data")
for {
invoiceSummary <- getInvoiceTransactionSummary(accountId)
unpaidInvoices <- identifyUnpaidInvoices(invoiceSummary.invoices)
} yield unpaidInvoices
}