public void RemoveNonExisting()
{
var lookup = new MutableLookup<string, string>();
lookup.Add(null, "blah");
lookup.Add(null, "monkeys");
lookup.Add("F", "Foo");
lookup.Add("F", "Foobar");
lookup.Add("B", "Bar");
Assert.IsFalse (lookup.Remove ("D"));
Assert.AreEqual(3, lookup.Count);
Assert.IsFalse (lookup.Remove ("F", "asdf"));
Assert.AreEqual(3, lookup.Count);
lookup.Remove (null);
Assert.IsFalse (lookup.Remove (null));
Assert.AreEqual (2, lookup.Count);
}