* identical inputs: This sounds like it ought to be a problem here, since the goals of this class
   * include testing that {@code equals()} is reflexive and is tolerant of {@code null}. However,
   * there's no problem. The reason: {@link EqualsTester} tests {@code null} and identical inputs
   * directly against {@code equals()} rather than through the {@code Equivalence}.
   */

   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class
   * include testing that {@code equals()} is reflexive and is tolerant of {@code null}. However,
   * there's no problem. The reason: {@link EqualsTester} tests {@code null} and identical inputs
   * directly against {@code equals()} rather than through the {@code Equivalence}.
   */

		// implies a cycle in the dominator graph. In the
		// example, x.Block dominates y.Block, y.Block dominates
		// z.Block, and z.Block dominates x.Block (treating
		// "dominates" as reflexive).  Cycles in the dominator
		// graph can only happen in an unreachable cycle.
	}