Idiomatic C# Fibonnaci

IdiomaticFibonacci.cs

// Written as a reply to https://twitter.com/buhakmeh/status/1577738711013335040
// (C) 2022 I D Griffiths

IEnumerable<BigInteger> FibonnaciEndless()
{
    BigInteger i = 0, n = 1;
    while (true)
    {
        yield return i;
        (i, n) = (n, i + n);
    }
}

// Why num + 1? Because Khalid's example also returns 11 numbers when you ask it
// for 10.
IEnumerable<BigInteger> Fibonnaci(int num) => FibonnaciEndless().Take(num + 1);

// ...and if you really want a list
IEnumerable<BigInteger> FibonnaciList(int num) => Fibonnaci(num).ToList();

foreach (BigInteger i in FibonnaciList(10))
{
    Console.WriteLine(i);
}