using System.Collections.Generic;
private List<string> _list = new List<string> { "A", "B", "C" };
public IReadOnlyList<string> List => _list;
public static void Main()
Console.Write("Before:");
foreach (string s in sc.List)
var enriched = EnrichCollection(sc.List);
foreach (string s in sc.List)
public static List<string> EnrichCollection(IEnumerable<string> collection)
var result = (collection is List<string> _list ? _list : collection?.ToList()) ?? new List<string>();