* to streams.
 *
 * @author Chris Povirk
 * @author Mike Bostock
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
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
@ElementTypesAreNonnullByDefault
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)));

    return Lists.newArrayList(contents);
  }

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

    return Lists.newArrayList(contents);
  }

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

      return range.contains(c);
    } catch (ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsAll(Collection<?> targets) {
    return Collections2.containsAllImpl(this, targets);
  }

  @Override
  public boolean isEmpty() {
    return false;
  }

  @Override

        return object != null && Collections2.safeContains(delegate, object);
      }

      @Override
      public boolean containsAll(Collection<?> collection) {
        return standardContainsAll(collection);
      }

      @Override
      public boolean remove(@CheckForNull Object object) {
        return object != null && Collections2.safeRemove(delegate, object);
      }

      @Override

import static com.google.common.collect.CollectPreconditions.checkNonnegative;
import static com.google.common.collect.Maps.immutableEntry;
import static java.util.Collections.unmodifiableList;
import static java.util.Collections.unmodifiableSet;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.MoreObjects;
import com.google.common.base.Predicate;

 */

/**
 * Collection interfaces and implementations, and other utilities for collections. This package is a
 * part of the open-source <a href="https://github.com/google/guava">Guava</a> library.
 *
 * <p>The classes in this package include:
 *
 * <h2>Immutable collections</h2>
 *
 * These are collections whose contents will never change. They also offer a few additional