*
   * <p>This differs from {@code Long.bitCount(x) == 1}, because {@code
   * Long.bitCount(Long.MIN_VALUE) == 1}, but {@link Long#MIN_VALUE} is not a power of two.
   */
  // Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
  @SuppressWarnings("ShortCircuitBoolean")
  public static boolean isPowerOfTwo(long x) {
    return x > 0 & (x & (x - 1)) == 0;
  }

  /**

import org.jspecify.annotations.Nullable;

/**
 * A test utility that verifies that your methods and constructors throw {@link
 * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a
 * parameter whose declaration or type isn't annotated with an annotation with the simple name
 * {@code Nullable}, {@code CheckForNull}, {@code NullableType}, or {@code NullableDecl}.
 *

      }
    }
  }

  /**
   * Returns a hash code, having the same bit length as each of the input hash codes, that combines
   * the information of these hash codes in an ordered fashion. That is, whenever two equal hash
   * codes are produced by two calls to this method, it is <i>as likely as possible</i> that each
   * was computed from the <i>same</i> input hash codes in the <i>same</i> order.
   *

   */
  Throwable failureCause();

  /**
   * Registers a {@link Listener} to be {@linkplain Executor#execute executed} on the given
   * executor. The listener will have the corresponding transition method called whenever the
   * service changes state. The listener will not have previous state changes replayed, so it is
   * suggested that listeners are added before the service starts.
   *

    assertThrows(IndexOutOfBoundsException.class, () -> iia3.subArray(-1, 1));
    assertThrows(IndexOutOfBoundsException.class, () -> iia3.subArray(1, 4));
  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...

  abstract @Nullable C leastValueAbove(DiscreteDomain<C> domain);

  abstract @Nullable C greatestValueBelow(DiscreteDomain<C> domain);

  /*
   * The canonical form is a BelowValue cut whenever possible, otherwise ABOVE_ALL, or
   * (only in the case of types that are unbounded below) BELOW_ALL.
   */
  Cut<C> canonical(DiscreteDomain<C> domain) {
    return this;
  }

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import org.jspecify.annotations.Nullable;

/** Implementations of {@code Futures.transform*}. */
@GwtCompatible
// Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
@SuppressWarnings("ShortCircuitBoolean")
abstract class AbstractTransformFuture<

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import org.jspecify.annotations.Nullable;

/** Implementations of {@code Futures.transform*}. */
@GwtCompatible
// Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
@SuppressWarnings("ShortCircuitBoolean")
abstract class AbstractTransformFuture<

   * processing and may run concurrently, for example, if the JVM flag {@code
   * -XX:+ExplicitGCInvokesConcurrent} is used.
   *
   * <p>Whenever possible, it is preferable to test directly for some observable change resulting
   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC

   * processing and may run concurrently, for example, if the JVM flag {@code
   * -XX:+ExplicitGCInvokesConcurrent} is used.
   *
   * <p>Whenever possible, it is preferable to test directly for some observable change resulting
   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC