C# Enumerable Split before running Parallel code

[Test]
public void SplitWithParallel()
{
  var list = new List<int>(new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10});
  list.Split(4).AsParallel().ForAll(x => x.ForEach(y => Console.WriteLine(y) /*or run a query*/));
}
 
public static class Extensions
{
  public static IEnumerable<IEnumerable<T>> Split<T>(this IEnumerable<T> list, int parts)
  {
    int i = 0;
    var splits = from item in list
      group item by i++%parts
      into part
      select part.AsEnumerable();
    return splits;
  }
 
  public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
  {
    foreach (var item in source)
    {
      action(item);
    }
  }
}