* to streams.
 *
 * @author Chris Povirk
 * @author Mike Bostock
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public final class Collections2 {
  private Collections2() {}

  /**
   * Returns the elements of {@code unfiltered} that satisfy a predicate. The returned collection is
   * a live view of {@code unfiltered}; changes to one affect the other.
   *

 * to streams.
 *
 * @author Chris Povirk
 * @author Mike Bostock
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public final class Collections2 {
  private Collections2() {}

  /**
   * Returns the elements of {@code unfiltered} that satisfy a predicate. The returned collection is
   * a live view of {@code unfiltered}; changes to one affect the other.
   *

    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));
    assertPermutationsCount(2, Collections2.permutations(newArrayList(1, 2)));
    assertPermutationsCount(6, Collections2.permutations(newArrayList(1, 2, 3)));
    assertPermutationsCount(5040, Collections2.permutations(newArrayList(1, 2, 3, 4, 5, 6, 7)));

    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));
    assertPermutationsCount(2, Collections2.permutations(newArrayList(1, 2)));
    assertPermutationsCount(6, Collections2.permutations(newArrayList(1, 2, 3)));
    assertPermutationsCount(5040, Collections2.permutations(newArrayList(1, 2, 3, 4, 5, 6, 7)));

      if (o instanceof Cell) {
        Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
        Map<C, V> row = safeGet(rowMap(), cell.getRowKey());
        return row != null
            && Collections2.safeContains(
                row.entrySet(), immutableEntry(cell.getColumnKey(), cell.getValue()));
      }
      return false;
    }

    @Override
    public boolean remove(@Nullable Object o) {

    return Lists.newArrayList(contents);
  }

  @Override
  Collection<Integer> filter(Collection<Integer> elements, Predicate<? super Integer> predicate) {
    return Collections2.filter(elements, predicate);
  }

   * implementation.
   *
   * @since 7.0
   */
  protected boolean standardContainsAll(Collection<?> collection) {
    return Collections2.containsAllImpl(this, collection);
  }

  /**
   * A sensible definition of {@link #addAll} in terms of {@link #add}. If you override {@link

   * implementation.
   *
   * @since 7.0
   */
  protected boolean standardContainsAll(Collection<?> collection) {
    return Collections2.containsAllImpl(this, collection);
  }

  /**
   * A sensible definition of {@link #addAll} in terms of {@link #add}. If you override {@link

      if (o instanceof Cell) {
        Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
        Map<C, V> row = safeGet(rowMap(), cell.getRowKey());
        return row != null
            && Collections2.safeContains(
                row.entrySet(), immutableEntry(cell.getColumnKey(), cell.getValue()));
      }
      return false;
    }

    @Override
    public boolean remove(@Nullable Object o) {

    return Lists.newArrayList(contents);
  }

  @Override
  Collection<Integer> filter(Collection<Integer> elements, Predicate<? super Integer> predicate) {
    return Collections2.filter(elements, predicate);
  }