### Question:
StringStack implements Iterable<String> { public boolean contains(String o) { for (String x: this) { if (x.equals(o)) return true; } return false; } StringStack(String... xs);  StringStack(Iterable<String> xs); int size(); boolean isEmpty(); boolean contains(String o); boolean add(String e); void clear(); String get(int index); int indexOf(String o); Iterator<String> iterator();  }### Answer:
@Test public void testContains() { assertFalse(new StringStack().contains("moo")); assertTrue(new StringStack("moo").contains("moo")); assertFalse(new StringStack("moo").contains("foobar")); assertTrue(new StringStack("foo", "moo").contains("foo")); }