Example of Unified Unit/Output

AddItemToCache.swift

class OnDiskCache {
 struct Item {
  let path: String
  let age: TimeInterval
  let size: Int
 }
 
 var currentItems: Set<Item> { /* .returning current items.. */ }
 
 func cleanCache(maxSize: Int) throws {
   let sortedItems = self.currentItems.sorted { $0.age < $1.age }
   var cumulativeSize = 0
   for item in sortedItems {
   cumulativeSize += item.size
   if cumulativeSize > maxSize {
     try FileManager.default.removeItem(atPath: item.path)
   }
  }
}