internal static Param <string> DoesNotStartWith(this Param <string> param, string s)
 {
     if (!Ensure.IsActive)
     {
         return(param);
     }
     if (param.Value.StartsWith(s))
     {
         throw ExceptionFactory.CreateForParamValidation(param, $"Must not start with {s}");
     }
     return(param);
 }