private IEnumerable <string> CallToYoungest(string[] userCommandArgs, int argsCount)
{
if (argsCount == 1)
{
var type = userCommandArgs[1];
if (!string.IsNullOrWhiteSpace(type))
{
yield return(animalCollection.RetrieveYoungest(type)?.ToString() ??
$"no animal of type {type}");
}
}
else if (argsCount == 0)
{
yield return(animalCollection.RetrieveYoungest().ToString());
}
}