[Pitch] Progress Reporting in Swift Concurrency

[ph1ps (Philipp Gabriel)]

I haven't fully read the proposal yet, however there are some instances where BasicProgress is passed in as optional. For instance:

@chloe-yeo

    private func chopFruits(progress: consuming BasicProgress?) async {
        // Initializes a progress reporter to report progress on chopping fruits 
        // with passed-in progress parameter 
        let choppingReporter = progress?.reporter(totalCount: fruits.count)
        for fruit in fruits {
            await fruit.chop()
            choppingReporter?.complete(count: 1)
        }
    }

In Detailed Design the assign function does not return an optional result:

public func assign(count: Int) -> ProgressReporter<Properties>.Progress

Would you mind clarifying, why it is optional in chopFruits and friends? Thank you.