I'm doing the Kotlin Koans and ran into this code:...

# getting-started

[thisen]

I'm doing the Kotlin Koans and ran into this code:

fun Shop.getCustomersWithMoreUndeliveredOrdersThanDelivered(): Set<Customer> {
    // Return customers who have more undelivered orders than delivered
    return customers.filter {
        val (delivered, undelivered) = it.orders.partition { it.isDelivered }
        undelivered.size > delivered.size
    }.toSet()
}

There's no return in the filter or anything. Can someone explain this?