* Executor)} on the input step.
 *
 * <h4>Catching</h4>
 *
 * To derive the next step from a failed input step, call {@link #catching(Class, ClosingFunction,
 * Executor)} or {@link #catchingAsync(Class, AsyncClosingFunction, Executor)} on the input step.
 *
 * <h4>Combining</h4>
 *
 * To derive a {@code ClosingFuture} from two or more input steps, pass the input steps to {@link

    protected A doBackward(B b) {
      return convert(bimap.inverse(), b);
    }

    private static <X, Y> Y convert(BiMap<X, Y> bimap, X input) {
      Y output = bimap.get(input);
      checkArgument(output != null, "No non-null mapping present for input: %s", input);
      return output;
    }

    @Override
    public boolean equals(@CheckForNull Object object) {