// vol. 2, Knuth, 4.2.2, (16) to the two-variable case. We have two value series x_i and y_i.
    // We define the arithmetic means X_n = 1/n \sum_{i=1}^n x_i, and Y_n = 1/n \sum_{i=1}^n y_i.
    // We also define the sum of the products of the differences from the means
    //           C_n = \sum_{i=1}^n x_i y_i - n X_n Y_n
    // for all n >= 1. Then for all n > 1:

                        + "stub-plugin-test, "
                        + "stub-plugin-package, "
                        + "stub-plugin-install], "
                        + "you should define versions in pluginManagement section of your pom.xml or parent");
    }

    @Test
    void testHandleBuildError() throws Exception {}

    @Test
    void testAttachToThread() throws Exception {}

    @Test

 * computeInPlace} instead of {@code compute}.
 *
 * <h3>Definition and notes on interpolation</h3>
 *
 * <p>The definition of the kth q-quantile of N values is as follows: define x = k * (N - 1) / q; if
 * x is an integer, the result is the value which would appear at index x in the sorted dataset
 * (unless there are {@link Double#NaN NaN} values, see below); otherwise, the result is the average

    assertThat(networkA.edgeOrder()).isEqualTo(networkB.edgeOrder());

    assertThat(networkA).isEqualTo(networkB);
  }

  /**
   * In some cases our graph implementations return custom sets that define their own size() and
   * contains(). Verify that these sets are consistent with the elements of their iterator.
   */
  @CanIgnoreReturnValue
  static <T> Set<T> sanityCheckSet(Set<T> set) {

    assertThat(networkA.edgeOrder()).isEqualTo(networkB.edgeOrder());

    assertThat(networkA).isEqualTo(networkB);
  }

  /**
   * In some cases our graph implementations return custom sets that define their own size() and
   * contains(). Verify that these sets are consistent with the elements of their iterator.
   */
  @CanIgnoreReturnValue
  static <T> Set<T> sanityCheckSet(Set<T> set) {

   * first decrementing to zero, and then removing. putIfAbsent or replace could observe the
   * intermediate zero-state. Ways we could deal with this are:
   *
   * - Don't define any of the ConcurrentMap operations. This is the current state of affairs.
   *
   * - Define putIfAbsent and replace as treating zero and absent identically (as currently
   *   implemented below). This is a bit surprising with putIfAbsent, which really becomes

 * that associates each key with a collection of values. All methods of {@link Multimap} are
 * supported, including those specified as optional in the interface.
 *
 * <p>To implement a multimap, a subclass must define the method {@link #createCollection()}, which
 * creates an empty collection of values for a key.
 *
 * <p>The multimap constructor takes a map that has a single entry for each distinct key. When you

     * @return file representing the tool executable, or null if the tool cannot be found
     */
    String findTool(String toolName);

    /**
     * Let the toolchain decide if it matches requirements defined
     * in the toolchain plugin configuration.
     * @param requirements Map<String, String> key value pair, may not be {@code null}

     * defined as:
     *
     * <pre>{@code
     * ((element == null) ? 0 : element.hashCode()) ^ count
     * }</pre>
     */
    @Override
    int hashCode();

    /**
     * Returns the canonical string representation of this entry, defined as follows. If the count

 *   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,
 * Callable)}, or {@link LoadingCache#getAll(Iterable)}.
 *
 * @author Charles Fry