public static async Task <ISequentialStore <T> > Create(IKeyValueStore <byte[], T> entityStore, string entityName, long defaultHeadOffset)
{
Preconditions.CheckNotNull(entityStore, nameof(entityStore));
Preconditions.CheckNonWhiteSpace(entityName, nameof(entityName));
Option <(byte[] key, T value)> firstEntry = await entityStore.GetFirstEntry(CancellationToken.None);
Option <(byte[] key, T value)> lastEntry = await entityStore.GetLastEntry(CancellationToken.None);
long MapLocalFunction((byte[] key, T) e) => StoreUtils.GetOffsetFromKey(e.key);
long headOffset = firstEntry.Map(MapLocalFunction).GetOrElse(defaultHeadOffset);
long tailOffset = lastEntry.Map(MapLocalFunction).GetOrElse(defaultHeadOffset - 1);
var sequentialStore = new SequentialStore <T>(entityStore, entityName, headOffset, tailOffset);
return(sequentialStore);
}