}

  /**
   * Creates an instance of {@link ToStringHelper}.
   *
   * <p>This is helpful for implementing {@link Object#toString()}. Specification by example:
   *
   * {@snippet :
   * // Returns "ClassName{}"
   * MoreObjects.toStringHelper(this)
   *     .toString();
   *
   * // Returns "ClassName{x=1}"
   * MoreObjects.toStringHelper(this)
   *     .add("x", 1)
   *     .toString();

/**
 * A builder of {@link ConcurrentMap} instances that can have keys or values automatically wrapped
 * in {@linkplain WeakReference weak} references.
 *
 * <p>Usage example:
 *
 * {@snippet :
 * ConcurrentMap<Request, Stopwatch> timers = new MapMaker()
 *     .concurrencyLevel(4)
 *     .weakKeys()
 *     .makeMap();
 * }
 *

   * in {@code occurrencesToRemove}. However, this operation <i>is</i> equivalent to, albeit
   * sometimes more efficient than, the following:
   *
   * {@snippet :
   * for (E e : occurrencesToRemove) {
   *   multisetToModify.remove(e);
   * }
   * }
   *
   * @return {@code true} if {@code multisetToModify} was changed as a result of this operation

   * in {@code occurrencesToRemove}. However, this operation <i>is</i> equivalent to, albeit
   * sometimes more efficient than, the following:
   *
   * {@snippet :
   * for (E e : occurrencesToRemove) {
   *   multisetToModify.remove(e);
   * }
   * }
   *
   * @return {@code true} if {@code multisetToModify} was changed as a result of this operation

        checkNotNull(value, "value"));
  }

  /**
   * A builder for creating immutable table instances, especially {@code public static final} tables
   * ("constant tables"). Example:
   *
   * {@snippet :
   * static final ImmutableTable<Integer, Character, String> SPREADSHEET =
   *     new ImmutableTable.Builder<Integer, Character, String>()
   *         .put(1, 'A', "foo")
   *         .put(1, 'B', "bar")

        checkNotNull(value, "value"));
  }

  /**
   * A builder for creating immutable table instances, especially {@code public static final} tables
   * ("constant tables"). Example:
   *
   * {@snippet :
   * static final ImmutableTable<Integer, Character, String> SPREADSHEET =
   *     new ImmutableTable.Builder<Integer, Character, String>()
   *         .put(1, 'A', "foo")
   *         .put(1, 'B', "bar")

 * its caller has made a mistake. This allows constructs such as
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }
 *
 * <p>to be replaced with the more compact
 *
 * {@snippet :
 * public static double sqrt(double value) {

@Immutable
public interface HashFunction {
  /**
   * Begins a new hash code computation by returning an initialized, stateful {@code Hasher}
   * instance that is ready to receive data. Example:
   *
   * {@snippet :
   * HashFunction hf = Hashing.md5();
   * HashCode hc = hf.newHasher()
   *     .putLong(id)
   *     .putBoolean(isActive)
   *     .hash();
   * }
   */
  Hasher newHasher();

  /**

    return new Builder<>();
  }

  /**
   * A builder for creating immutable multiset instances, especially {@code public static final}
   * multisets ("constant multisets"). Example:
   *
   * {@snippet :
   * public static final ImmutableMultiset<Bean> BEANS =
   *     new ImmutableMultiset.Builder<Bean>()
   *         .addCopies(Bean.COCOA, 4)
   *         .addCopies(Bean.GARDEN, 6)

 * its caller has made a mistake. This allows constructs such as
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }
 *
 * <p>to be replaced with the more compact
 *
 * {@snippet :
 * public static double sqrt(double value) {