Sample for the NetFabric.Hyperlinq Post.Mortem article

Count.IValueEnumerable.cs

public static int Count<TEnumerable, TEnumerator, TSource>(this TEnumerable source)
    where TEnumerable : IValueEnumerable<TSource, TEnumerator>
    where TEnumerator : struct, IEnumerator<TSource>
{
    using var enumerator = source.GetEnumerator();
    var count = 0;
    while (enumerator.MoveNext())
        count++;
    return count;
} 

public static int Count<T>(this IEnumerable<T> source)
{
    using var enumerator = source.GetEnumerator();
    var count = 0;
    while(enumerator.MoveNext())
        count++;
    return count;
}