Appendable secretlyAWriter = new StringWriter();
    result = CharStreams.asWriter(secretlyAWriter);
    assertSame(secretlyAWriter, result);
  }

  // CharStreams.copy has type specific optimizations for Readers,StringBuilders and Writers

  public void testCopy() throws IOException {
    StringBuilder builder = new StringBuilder();
    long copied =
        CharStreams.copy(

    Appendable secretlyAWriter = new StringWriter();
    result = CharStreams.asWriter(secretlyAWriter);
    assertSame(secretlyAWriter, result);
  }

  // CharStreams.copy has type specific optimizations for Readers,StringBuilders and Writers

  public void testCopy() throws IOException {
    StringBuilder builder = new StringBuilder();
    long copied =
        CharStreams.copy(

      frequency.set(0);
    }
    backingMap.clear();
    size = 0L;
  }

  @Override
  int distinctElements() {
    return backingMap.size();
  }

  // Optimizations - Query Operations

  @Override
  public int size() {
    return Ints.saturatedCast(size);
  }

  @Override
  public Iterator<E> iterator() {
    return new MapBasedMultisetIterator();
  }

    checkElementIndex(index, size);
    // requireNonNull is safe because we guarantee that the first `size` elements are non-null.
    return (E) requireNonNull(array[index]);
  }

  // TODO(lowasser): benchmark optimizations for equals() and see if they're worthwhile

  // redeclare to help optimizers with b/310253115
  @SuppressWarnings("RedundantOverride")
  @Override
  @J2ktIncompatible // serialization

    implements ListenableFuture<V> {

  static final boolean GENERATE_CANCELLATION_CAUSES = false;

  /**
   * Tag interface marking trusted subclasses. This enables some optimizations. The implementation
   * of this interface must also be an AbstractFuture and must not override or expose for overriding
   * any of the public methods of ListenableFuture.
   */

import java.io.StringWriter;
import java.nio.Buffer;
import java.nio.CharBuffer;
import java.util.Random;

/**
 * Benchmarks for {@link CharStreams#copy}.
 *
 * <p>{@link CharStreams#copy} has type specific optimizations for various common Appendable and
 * Reader implementations, this compares the performance of the different options.
 */
// These benchmarks allocate a lot of data so use a large heap
@VmOptions({"-Xms12g", "-Xmx12g", "-d64"})

import java.io.StringWriter;
import java.nio.Buffer;
import java.nio.CharBuffer;
import java.util.Random;

/**
 * Benchmarks for {@link CharStreams#copy}.
 *
 * <p>{@link CharStreams#copy} has type specific optimizations for various common Appendable and
 * Reader implementations, this compares the performance of the different options.
 */
// These benchmarks allocate a lot of data so use a large heap
@VmOptions({"-Xms12g", "-Xmx12g", "-d64"})

       * need access to the futures again, so we can just pass `null`.
       *
       * TODO(b/112550045): Allocating a single, cheaper listener is (I think) only an optimization.
       * If we make some other optimizations, this one will no longer be necessary. The optimization
       * could actually hurt in some cases, as it forces us to keep all inputs in memory until the
       * final input completes.
       */

   * be updated after modifications to {@code graph}.
   *
   * @since 33.1.0 (present with return type {@code Graph} since 20.0)
   */
  // TODO(b/31438252): Consider potential optimizations for this algorithm.
  public static <N> ImmutableGraph<N> transitiveClosure(Graph<N> graph) {
    ImmutableGraph.Builder<N> transitiveClosure =
        GraphBuilder.from(graph).allowsSelfLoops(true).<N>immutable();

    return new Inverse<>(backward, this);
  }

  void setInverse(AbstractBiMap<V, K> inverse) {
    this.inverse = inverse;
  }

  // Query Operations (optimizations)

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    return inverse.containsKey(value);
  }

  // Modification Operations

  @CanIgnoreReturnValue
  @Override