Funky Lööps.cs

using System;
using System.Collections.Generic;

public static class VonNeumannExtensions
{
	public static IEnumerator<int> GetEnumerator(this int number)
	{
		for (var i = 0; i < number; i++)
		{
			yield return i;	
		}
	}
    
    public static IEnumerator<int> GetEnumerator(this Range range) 
    {
         for (var i = range.Start.Value; i < range.End.Value; i++) 
         {
             yield return i;
         }
    }
}

public static class Program {
    public static void Main() {
        
        foreach (var i in 3..7) {
             Console.WriteLine(i);   
        }
        
        Console.WriteLine("---");
        
        foreach (var i in 7) {
             Console.WriteLine(i);   
        }
        
    }
}

​Funky Lööps.output.txt

3
4
5
6
---
0
1
2
3
4
5
6

​​.sharplab.json

{
    "version": 1,
    "target": "Run",
    "mode": "Release",
    "branch": "master"
}