*
   * {@snippet :
   * b ---- a ---- d
   * |      |
   * |      |
   * e ---- c ---- f
   * }
   */
  private static final SuccessorsFunction<Character> JAVADOC_GRAPH =
      createUndirectedGraph("ba", "ad", "be", "ac", "ec", "cf");

  /**
   * A diamond shaped directed graph (arrows going down):
   *
   * {@snippet :
   *   a
   *  / \
   * b   c
   *  \ /

   *
   * {@snippet :
   * b ---- a ---- d
   * |      |
   * |      |
   * e ---- c ---- f
   * }
   */
  private static final SuccessorsFunction<Character> JAVADOC_GRAPH =
      createUndirectedGraph("ba", "ad", "be", "ac", "ec", "cf");

  /**
   * A diamond shaped directed graph (arrows going down):
   *
   * {@snippet :
   *   a
   *  / \
   * b   c
   *  \ /

import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ListenableFuture} that supports fluent chains of operations. For example:
 *
 * {@snippet :
 * ListenableFuture<Boolean> adminIsLoggedIn =
 *     FluentFuture.from(usersDatabase.getAdminUser())
 *         .transform(User::getId, directExecutor())
 *         .transform(ActivityService::isLoggedIn, threadPool)

 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * {@snippet :
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {
 *     return new ForwardingFoo(foo);
 *   }
 * });
 * }
 *
 * @author Ben Yu

   * respective source streams. For example:
   *
   * {@snippet :
   * Streams.forEachPair(
   *   Stream.of("foo1", "foo2", "foo3"),
   *   Stream.of("bar1", "bar2"),
   *   (arg1, arg2) -> System.out.println(arg1 + ":" + arg2)
   * }
   *
   * <p>will print:
   *
   * {@snippet :
   * foo1:bar1
   * foo2:bar2
   * }
   *

   * java.util.stream} Javadoc), that order is preserved, but entries are <a
   * href="ImmutableMultimap.html#iteration">grouped by key</a>.
   *
   * <p>Example:
   *
   * {@snippet :
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")

   * the beginning and from the end of the string. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("ab").trimFrom("abacatbab")
   * }
   *
   * ... returns {@code "cat"}.
   *
   * <p>Note that:
   *
   * {@snippet :
   * CharMatcher.inRange('\0', ' ').trimFrom(str)
   * }
   *
   * ... is equivalent to {@link String#trim()}.
   */

   * and not contents.
   *
   * <p>This is useful for implementing {@link Object#hashCode()}. For example, in an object that
   * has three properties, {@code x}, {@code y}, and {@code z}, one could write:
   *
   * {@snippet :
   * public int hashCode() {
   *   return Objects.hashCode(getX(), getY(), getZ());
   * }
   * }
   *
   * <p><b>Warning:</b> When a single object is supplied, the returned hash code does not equal the

 * as a {@code List}:
 *
 * {@snippet :
 * ImmutableList<String> results =
 *     FluentIterable.from(database.getClientList())
 *         .filter(Client::isActiveInLastMonth)
 *         .transform(Object::toString)
 *         .limit(10)
 *         .toList();
 * }
 *
 * The approximate stream equivalent is:
 *
 * {@snippet :
 * List<String> results =
 *     database.getClientList()

 * as a {@code List}:
 *
 * {@snippet :
 * ImmutableList<String> results =
 *     FluentIterable.from(database.getClientList())
 *         .filter(Client::isActiveInLastMonth)
 *         .transform(Object::toString)
 *         .limit(10)
 *         .toList();
 * }
 *
 * The approximate stream equivalent is:
 *
 * {@snippet :
 * List<String> results =
 *     database.getClientList()