C# implementation of Seq.pairwise

gistfile1.cs

public static IEnumerable<Tuple<T, T>> Pairwise<T>(this IEnumerable<T> source)
{
    if (source == null)
    {
        throw new ArgumentNullException("source");
    }

    var previous = default(T);

    using (var enumerator = source.GetEnumerator())
    {
        if (enumerator.MoveNext())
        {
            previous = enumerator.Current;
        }

        while (enumerator.MoveNext())
        {
            yield return Tuple.Create(previous, enumerator.Current);
            previous = enumerator.Current;
        }
    }
}