System.out.println("hit rate: " + hit / req);
  }

  // for proper distributions later:
  // import JSci.maths.statistics.ProbabilityDistribution;
  // int key = (int) dist.inverse(random.nextDouble());

      super(delegate, predicate);
      this.inverse =
          new FilteredEntryBiMap<>(delegate.inverse(), inversePredicate(predicate), this);
    }

    private FilteredEntryBiMap(
        BiMap<K, V> delegate, Predicate<? super Entry<K, V>> predicate, BiMap<V, K> inverse) {
      super(delegate, predicate);
      this.inverse = inverse;
    }

    BiMap<K, V> unfiltered() {

      super(delegate, predicate);
      this.inverse =
          new FilteredEntryBiMap<>(delegate.inverse(), inversePredicate(predicate), this);
    }

    private FilteredEntryBiMap(
        BiMap<K, V> delegate, Predicate<? super Entry<K, V>> predicate, BiMap<V, K> inverse) {
      super(delegate, predicate);
      this.inverse = inverse;
    }

    BiMap<K, V> unfiltered() {

   */
  @Override
  public ImmutableSetMultimap<V, K> inverse() {
    ImmutableSetMultimap<V, K> result = inverse;
    return (result == null) ? (inverse = invert()) : result;
  }

  private ImmutableSetMultimap<V, K> invert() {
    Builder<V, K> builder = builder();
    for (Entry<K, V> entry : entries()) {
      builder.put(entry.getValue(), entry.getKey());
    }

    BiMap<K, V> bimap = (BiMap<K, V>) map;

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());

        return delegate().forcePut(key, value);
      }
    }

    @Override
    public BiMap<V, K> inverse() {
      synchronized (mutex) {
        if (inverse == null) {
          inverse = new SynchronizedBiMap<>(delegate().inverse(), mutex, this);
        }
        return inverse;
      }
    }

    private static final long serialVersionUID = 0;
  }

        return delegate().forcePut(key, value);
      }
    }

    @Override
    public BiMap<V, K> inverse() {
      synchronized (mutex) {
        if (inverse == null) {
          inverse = new SynchronizedBiMap<>(delegate().inverse(), mutex, this);
        }
        return inverse;
      }
    }

    private static final long serialVersionUID = 0;
  }

    return fromLongBits(value);
  }

  /**
   * Returns a {@code UnsignedLong} representing the same value as the specified {@code BigInteger}.
   * This is the inverse operation of {@link #bigIntegerValue()}.
   *
   * @throws IllegalArgumentException if {@code value} is negative or {@code value >= 2^64}
   */
  @CanIgnoreReturnValue
  public static UnsignedLong valueOf(BigInteger value) {

    return fromLongBits(value);
  }

  /**
   * Returns a {@code UnsignedLong} representing the same value as the specified {@code BigInteger}.
   * This is the inverse operation of {@link #bigIntegerValue()}.
   *
   * @throws IllegalArgumentException if {@code value} is negative or {@code value >= 2^64}
   */
  @CanIgnoreReturnValue
  public static UnsignedLong valueOf(BigInteger value) {

import javax.annotation.CheckForNull;

/**
 * An {@link Escaper} that converts literal text into a format safe for inclusion in a particular
 * context (such as an XML document). Typically (but not always), the inverse process of
 * "unescaping" the text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code