import java.util.SortedMap;
import java.util.function.BiFunction;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A navigable map which forwards all its method calls to another navigable map. Subclasses should
 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

import java.util.NoSuchElementException;
import java.util.SortedMap;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A navigable map which forwards all its method calls to another navigable map. Subclasses should
 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

import java.util.TreeSet;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A wrapper around {@code TreeSet} that aggressively checks to see if elements are mutually
 * comparable. This implementation passes the navigable set test suites.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")

import java.util.TreeSet;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A wrapper around {@code TreeSet} that aggressively checks to see if elements are mutually
 * comparable. This implementation passes the navigable set test suites.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")

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
public final class SafeTreeMap<K, V> implements Serializable, NavigableMap<K, V> {
  @SuppressWarnings("unchecked")

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
public final class SafeTreeMap<K, V> implements Serializable, NavigableMap<K, V> {
  @SuppressWarnings("unchecked")

   * display. This includes two values for each extreme.
   *
   * <p>This method (dangerously) assume that the strings {@code "!! a"} and {@code "~~ z"} will
   * work for this purpose, which may cause problems for navigable maps with non-string or unicode
   * generators.
   */
  private List<String> getExtremeValues() {
    List<String> result = new ArrayList<>();
    result.add("!! a");
    result.add("!! b");

   * display. This includes two values for each extreme.
   *
   * <p>This method (dangerously) assume that the strings {@code "!! a"} and {@code "~~ z"} will
   * work for this purpose, which may cause problems for navigable maps with non-string or unicode
   * generators.
   */
  private List<String> getExtremeValues() {
    List<String> result = new ArrayList<>();
    result.add("!! a");
    result.add("!! b");