@Override
          protected char[] escapeUnsafe(int c) {
            return NO_CHARS;
          }
        };
    EscaperAsserts.assertBasic(escaper);
    assertEquals("<tab>Fish <and> Chips<newline>", escaper.escape("\tFish & Chips\n"));

    // Verify that everything else is left unescaped.
    String safeChars = "\0\u0100\uD800\uDC00\uFFFF";
    assertEquals(safeChars, escaper.escape(safeChars));

          @Override
          protected char[] escapeUnsafe(int c) {
            return NO_CHARS;
          }
        };
    EscaperAsserts.assertBasic(escaper);
    assertEquals("<tab>Fish <and> Chips<newline>", escaper.escape("\tFish & Chips\n"));

    // Verify that everything else is left unescaped.
    String safeChars = "\0\u0100\uD800\uDC00\uFFFF";
    assertEquals(safeChars, escaper.escape(safeChars));

    // Replacements are applied first regardless of whether the character is in
    // the safe range or not ('&' is a safe char while '\t' and '\n' are not).
    assertEquals(
        "<tab>Fish <and>? Chips?<newline>", replacingEscaper.escape("\tFish &\0 Chips\r\n"));
  }

    // Replacements are applied first regardless of whether the character is in
    // the safe range or not ('&' is a safe char while '\t' and '\n' are not).
    assertEquals(
        "<tab>Fish <and>? Chips?<newline>", replacingEscaper.escape("\tFish &\0 Chips\r\n"));
  }

  }

  /**
   * A sensible definition of {@link #lower} in terms of the {@code descendingIterator} method of
   * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
   * wish to override {@link #lower} to forward to this implementation.
   */
  @CheckForNull
  protected E standardLower(@ParametricNullness E e) {
    return Iterators.getNext(headSet(e, false).descendingIterator(), null);
  }

   * #clear} to forward to this implementation.
   *
   * @since 7.0
   */
  protected void standardClear() {
    Iterators.clear(iterator());
  }

  /**
   * A sensible definition of {@link #isEmpty} as {@code !iterator().hasNext}. If you override
   * {@link #isEmpty}, you may wish to override {@link #isEmpty} to forward to this implementation.

   * #clear} to forward to this implementation.
   *
   * @since 7.0
   */
  protected void standardClear() {
    Iterators.clear(iterator());
  }

  /**
   * A sensible definition of {@link #isEmpty} as {@code !iterator().hasNext}. If you override
   * {@link #isEmpty}, you may wish to override {@link #isEmpty} to forward to this implementation.

  }

  /**
   * A sensible definition of {@link #lower} in terms of the {@code descendingIterator} method of
   * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
   * wish to override {@link #lower} to forward to this implementation.
   */
  @CheckForNull
  protected E standardLower(@ParametricNullness E e) {
    return Iterators.getNext(headSet(e, false).descendingIterator(), null);
  }

   * this implementation.
   *
   * @since 7.0
   */
  protected Iterator<E> standardIterator() {
    return listIterator();
  }

  /**
   * A sensible default implementation of {@link #listIterator()}, in terms of {@link
   * #listIterator(int)}. If you override {@link #listIterator(int)}, you may wish to override

    return delegate().tailMap(fromKey);
  }

  /**
   * A sensible implementation of {@link SortedMap#keySet} in terms of the methods of {@code
   * ForwardingSortedMap}. In many cases, you may wish to override {@link
   * ForwardingSortedMap#keySet} to forward to this implementation or a subclass thereof.
   *
   * @since 15.0
   */
  protected class StandardKeySet extends Maps.SortedKeySet<K, V> {