int len = sequence.length();
    int first;
    int last;

    for (first = 0; first < len; first++) {
      if (!matches(sequence.charAt(first))) {
        break;
      }
    }
    for (last = len - 1; last > first; last--) {
      if (!matches(sequence.charAt(last))) {
        break;
      }
    }

    return sequence.subSequence(first, last + 1).toString();
  }

  /**

    int len = sequence.length();
    int first;
    int last;

    for (first = 0; first < len; first++) {
      if (!matches(sequence.charAt(first))) {
        break;
      }
    }
    for (last = len - 1; last > first; last--) {
      if (!matches(sequence.charAt(last))) {
        break;
      }
    }

    return sequence.subSequence(first, last + 1).toString();
  }

  /**

 *
 * <ul>
 *   <li>automatic loading of entries into the cache
 *   <li>least-recently-used eviction when a maximum size is exceeded (note that the cache is
 *       divided into segments, each of which does LRU internally)
 *   <li>time-based expiration of entries, measured since last access or last write
 *   <li>keys automatically wrapped in {@code WeakReference}

      }
    }

    /**
     * Throws UnsupportedOperationException. A future version may support this operation. Then the
     * value for any given key will be the one that was last supplied in a {@code put} operation for
     * that key.
     *
     * @throws UnsupportedOperationException always
     * @since 31.1
     * @deprecated This method is not currently implemented, and may never be.

          array[i] = null; // for GWT
        }

        List<@Nullable T> list = Collections.unmodifiableList(Arrays.asList(array));
        // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
        if (pad || count == size) {
          return list;
        } else {
          return list.subList(0, count);
        }
      }
    };
  }

  /**

    }

    @Override
    protected Collection<List<E>> delegate() {
      return delegate;
    }

    @Override
    public boolean contains(@CheckForNull Object object) {
      if (!(object instanceof List)) {
        return false;
      }
      List<?> list = (List<?>) object;
      if (list.size() != axes.size()) {
        return false;
      }
      int i = 0;

            list(0, 0, 0),
            list(0, 0, 1),
            list(0, 1, 0),
            list(0, 1, 1),
            list(1, 0, 0),
            list(1, 0, 1),
            list(1, 1, 0),
            list(1, 1, 1))
        .inOrder();
  }

  public void testCartesianProduct_contains() {
    Set<List<Integer>> actual = Sets.cartesianProduct(set(1, 2), set(3, 4));
    assertTrue(actual.contains(list(1, 3)));

      }
    }

    @Override
    public E last() {
      synchronized (mutex) {
        return delegate().last();
      }
    }

    private static final long serialVersionUID = 0;
  }

  private static <E extends @Nullable Object> List<E> list(
      List<E> list, @CheckForNull Object mutex) {
    return (list instanceof RandomAccess)

          // Single node on list
          if (next == null) {
            newTable.set(headIndex, head);
          } else {
            // Reuse the consecutive sequence of nodes with the same target
            // index from the end of the list. tail points to the first
            // entry in the reusable list.
            E tail = head;
            int tailIndex = headIndex;

      }
    }

    /**
     * Throws UnsupportedOperationException. A future version may support this operation. Then the
     * value for any given key will be the one that was last supplied in a {@code put} operation for
     * that key.
     *
     * @throws UnsupportedOperationException always
     * @since 31.1
     * @deprecated This method is not currently implemented, and may never be.