/// <summary>
/// Initialises a new weighted collection with the provided items,
/// all having the same weight of 1.
/// </summary>
/// <param name="collection">The items which should be part of the collection.
/// </param>
/// <exception cref="ArgumentNullException">If the given collection does not
/// exist.</exception>
public WeightedCollection(IEnumerable <T> collection)
: this(collection, Enumerators.Infinite(0d))
{
}