@Test
public void testRemoveIf() {

	this.set.removeIf(s -> "c".equals(s));
	assertFalse("c was removed but contains still says it's in.", this.set.contains("c"));
	assertTrue("Since c was removed from the set, d before a should be allowed but isn't.", this.set.allowsABeforeB(D, A));
	assertTrue("Since c was removed from the set, d before b should be allowed but isn't.", this.set.allowsABeforeB(D, B));
}