SortedBucketCollection: A memory efficient SortedList accepting multiple items with the same key

Sometimes, the collections available cannot meet your requirements and you have to write your own. This article explains how to write your own collection in detail, covering some advanced topics. The implemented collection works like a SortedDirectory, but allows for 2 keys per item and only the combination of the 2 keys needs to be unique. This is helpful when for example items should be stored and retrieved per day when they were created.