@Test
 public void makeString() {
   ImmutableBag<String> bag = this.newBag();
   Assert.assertEquals(FastList.newList(bag).makeString(), bag.makeString());
   Assert.assertEquals(bag.toString(), '[' + bag.makeString() + ']');
   Assert.assertEquals(bag.toString(), '[' + bag.makeString(", ") + ']');
   Assert.assertEquals(bag.toString(), bag.makeString("[", ", ", "]"));
 }