internal MutableLookup<string, string> GetTestLookup()
{
var lookup = new MutableLookup<string, string>();
lookup.Add (null, (string)null);
lookup.Add (null, "blah");
lookup.Add (null, "monkeys");
lookup.Add ("F", "Foo");
lookup.Add ("F", "Foobar");
lookup.Add ("B", "Bar");
return lookup;
}