public static Span <T> ToSpan <T>(this Vec128 <T> src) where T : struct => src.ToSpan128();
public static Vec128 <T> Replicate <T>(this Vec128 <T> src) where T : unmanaged => Vec128.Load(src.ToSpan128());
public static Span <T> ToSpan <T>(this Vec128 <T> src) where T : struct => src.ToSpan128();
public static Vec128 <T> Replicate <T>(this Vec128 <T> src) where T : unmanaged => Vec128.Load(src.ToSpan128());