new LineProcessor<Integer>() {
          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            sb.append(line);
            return seen < 2;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };

        new LineProcessor<Integer>() {
          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            sb.append(line);
            return seen < 2;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };

import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;
import java.io.Writer;

/**
 * Unit test for {@link AppendableWriter}.
 *
 * @author Alan Green
 */
public class AppendableWriterTest extends IoTestCase {

  /** Helper class for testing behavior with Flushable and Closeable targets. */
  private static class SpyAppendable implements Appendable, Flushable, Closeable {

   * range [0, k) and ignore the remaining elements.
   */
  private final @Nullable T[] buffer;
  private int bufferSize;

  /**
   * The largest of the lowest k elements we've seen so far relative to this comparator. If
   * bufferSize ≥ k, then we can ignore any elements greater than this value.
   */
  @CheckForNull private T threshold;

    }

    // ensures that the number of invocations looks sane
    void assertInvariants(int expectedBytes) {
      // we should have seen as many bytes as the next multiple of chunk after expectedBytes - 1
      assertEquals(out.toByteArray().length, ceilToMultiple(expectedBytes, chunkSize));
      assertEquals(expectedBytes / chunkSize, processCalled);

   *
   * <p>This class is accessible but not supported in GWT as it references {@link
   * PermittedMetaException}.
   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed
    // TODO: verify contents afterward
    // TODO: something shiny and new instead of Stack
    // TODO: test whether null is supported (create a Feature)
    /**

             * exception in seenExceptions. When we complete secondFuture with the same exception,
             * we want for AggregateFuture to still detect that it's been previously seen.
             */
            secondFuture.setException(sameInstance);
          }
        },
        directExecutor());
    firstFuture.setException(sameInstance);

    try {

  /** Adds the chain to the seen set, and returns whether all the chain was new to us. */
  private static boolean addCausalChain(Set<Throwable> seen, Throwable param) {
    // Declare a "true" local variable so that the Checker Framework will infer nullness.
    Throwable t = param;

    for (; t != null; t = t.getCause()) {
      boolean firstTimeSeen = seen.add(t);
      if (!firstTimeSeen) {
        /*

       */
      seenExceptionsLocal = requireNonNull(seenExceptions);
    }
    return seenExceptionsLocal;
  }

  /** Populates {@code seen} with the exception that was passed to {@code setException}. */
  abstract void addInitialException(Set<Throwable> seen);

  final int decrementRemainingAndGet() {
    return ATOMIC_HELPER.decrementAndGetRemainingCount(this);
  }

  final void clearSeenExceptions() {

   *       of nodes that have thus far been visited), plus <i>O(H)</i> space (where <i>H</i> is the
   *       number of nodes that have been seen but not yet visited, that is, the "horizon").
   * </ul>
   *
   * @param graph {@link SuccessorsFunction} representing a general graph that may have cycles.
   */