public static IMemoryOwner <T> Slice <T>(this IMemoryOwner <T> that, int offset, int length)
{
if (!(that is CountdownMemoryOwner <T>))
{
// other types of IMemoryOwner may return Memory instance to pool and give it to other side for use
throw new InvalidOperationException(
$"Passed memory owner type '{that.GetType().FullName}' isn't supported.");
}
// wrap it with another countdown to support slicing
return(that.AsCountdown(offset, length));
}