* See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.concurrent

import assertk.assertThat
import assertk.assertions.isEqualTo
import java.io.Closeable
import java.util.AbstractQueue
import java.util.concurrent.BlockingQueue
import java.util.concurrent.Executors
import java.util.concurrent.TimeUnit

   * ...
   * ImmutableSet<Color> allColors = ImmutableSet.of(red, green, blue);
   *
   * ImmutableMap<String, Color> colorForName =
   *     uniqueIndex(allColors, c -> c.toString());
   * assertThat(colorForName).containsEntry("red", red);
   * }</pre>
   *
   * <p>If your index may associate multiple values with each key, use {@link
   * Multimaps#index(Iterable, Function) Multimaps.index}.
   *