V value,
      BinaryOperator<V> mergeFunction) {
    checkNotNull(value);
    V oldValue = table.get(row, column);
    if (oldValue == null) {
      table.put(row, column, value);
    } else {
      V newValue = mergeFunction.apply(oldValue, value);
      if (newValue == null) {
        table.remove(row, column);
      } else {
        table.put(row, column, newValue);
      }
    }
  }

import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A wrapper around {@code TreeMap} that aggressively checks to see if keys are mutually comparable.
 * This implementation passes the navigable map test suites.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible

import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A wrapper around {@code TreeMap} that aggressively checks to see if keys are mutually comparable.
 * This implementation passes the navigable map test suites.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible

          new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
              runLatch.countDown();
              taskLatch.await();
              if (throwException) {
                throw new IllegalStateException("Fail");
              }
              return 25;
            }
          });

  @Override
  protected void setUp() throws Exception {

    List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));
    }
  }

  @Override
  final void handleAllCompleted() {
    List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      set(combine(localValues));
    }
  }

  @Override

    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'b');

    // Iterate again to see if calculation is done again
    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'a', 'b', 'b');
  }

  @Test

      }
      double mean = accumulator.mean();
      double meanByAddAllStats = accumulatorByAddAllStats.mean();
      if (values.hasAnyNaN()) {
        assertWithMessage("mean of " + values).that(mean).isNaN();
        assertWithMessage("mean by addAll(Stats) of " + values).that(meanByAddAllStats).isNaN();
      } else if (values.hasAnyPositiveInfinity() && values.hasAnyNegativeInfinity()) {

      if (map.isEmpty()) {
        return of();
      }
      return new RegularImmutableBiMap<K, V>(super.buildOrThrow());
    }

    @Override
    ImmutableBiMap<K, V> buildJdkBacked() {
      return build();
    }
  }

  public static <K, V> ImmutableBiMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
    if (map instanceof ImmutableBiMap) {

    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }

  @Override
  @ParametricNullness
  public K firstKey() {
    Entry<K, V> entry = firstEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();
    }
  }

  @Override
  @ParametricNullness
  public K lastKey() {
    Entry<K, V> entry = lastEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();