/// <summary>
/// Returns the cartesian product of the two collections <c>c1</c>
/// and <c>c2</c>.
/// </summary>
/// <param name="c1">Should not be null.</param>
/// <param name="c2">Should not be null.</param>
public static ICollection Product(ICollection c1, ICollection c2)
{
if(c1 == null)
{
throw new ArgumentNullException("c1", string.Format(Resources.ArgumentNull, "c1"));
}

if(c2 == null)
{
throw new ArgumentNullException("c2", string.Format(Resources.ArgumentNull, "c2"));
}

return null;
}