var map = new Map<int, string>();
map.Add(42, "Hello");
Console.WriteLine(map.Forward[42]); // Outputs "Hello"
Console.WriteLine(map.Reverse["Hello"]); //Outputs 42
 ```

+ <a href="https://www.nuget.org/packages/MoreCollections.CircularList">MoreCollections.CircularList</a>  
List which supports modulo indexing.

``` csharp
var list = new string[]{"one", "two", "three"}.ToList();

var circularList = list.ToCircularList();
Console.WriteLine(circularList[-1]); //outputs "three"
Console.WriteLine(circularList[6]); //outputs "one"

var hist = new History<string>(maxCount: 2);

hist.Add("one");
hist.Add("two");
hist.Add("three");

//outputs: "three", "two"
foreach(var item in hist)
{
   Console.Write(" " + item);
}

var arr = new string[]{"three", "one", "two"};
var indexes = new int[]{1, 2, 0};

var indexedCollection = new IndexedCollection<string>(arr, indexes);

//outputs: "one", "two", "three"
foreach(var item in indexedCollection)
{
   Console.Write(" " + item);
}

var arr = new Point[]{new Point(0, 0), new Point(1, 2) }; //point is struct for (x,y) pair

var pinnedArray = new PinnedArray<Point>(arr); //data is shared

unsafe
{
   Point* pt = (Point*)pinnedArray.Data;
   pt->X = 3;
}

Console.WriteLine(arr[0].X); //outputs "3"

var lazyMatrixCache = new  LazyMemoryCache<int, double[,]>(maxMemoryOccupation: 0.8f);

//load items by calling lazyMatrixCache.AddOrUpdate(<key>, <matrix constructor>)

Console.WriteLine("Is element loaded: " + lazyMatrixCache[10].IsValueCreated); //false
Console.WriteLine("Item (0,0) value: "  + lazyMatrixCache[10].Value[0,0]); //value at (0,0)
Console.WriteLine("Is element loaded: " + lazyMatrixCache[10].IsValueCreated); //true

//elements are automatically evicted if RAM occupation exceeds 80%