tester.testForwarding(
        Arithmetic.class,
        new Function<Arithmetic, Arithmetic>() {
          @Override
          public Arithmetic apply(Arithmetic arithmetic) {
            return new ForwardingArithmetic(arithmetic);
          }
        });
    tester.testForwarding(
        ParameterTypesDifferent.class,
        new Function<ParameterTypesDifferent, ParameterTypesDifferent>() {
          @Override

    final BarChild barChild = new BarChild();
    Function<Foo, BarChild> function =
        new Function<Foo, BarChild>() {
          @Override
          public BarChild apply(Foo unused) {
            return barChild;
          }
        };
    Bar bar = getDone(transform(future, function, directExecutor()));
    assertSame(barChild, bar);
  }

  /*

import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

   *
   * @param function A Function to transform the results of this future to the results of the
   *     returned future.
   * @param executor Executor to run the function in.
   * @return A future that holds result of the transformation.
   */
  public final <T extends @Nullable Object> FluentFuture<T> transform(
      Function<? super V, T> function, Executor executor) {

        }
      };

  /* Helper function to make a BigInteger value from a Long. */
  private static final Function<Long, BigInteger> TO_BIGINTEGER =
      new Function<Long, BigInteger>() {
        @Override
        public BigInteger apply(Long n) {
          return BigInteger.valueOf(n);
        }
      };

  private static final Function<Integer, Integer> NEGATE_INT =
      new Function<Integer, Integer>() {
        @Override

          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    throw new UnsupportedOperationException();
  }

  /**
   * Not supported. This method does not make sense for {@code BiMap}. This method exists only to
   * hide {@link ImmutableMap#toImmutableMap(Function, Function, BinaryOperator)} from consumers of

   *     escaped for any other reason
   */
  public abstract String escape(String string);

  private final Function<String, String> asFunction = this::escape;

  /** Returns a {@link Function} that invokes {@link #escape(String)} on this escaper. */
  public final Function<String, String> asFunction() {
    return asFunction;
  }

  }

  /**
   * Returns a cache loader that uses {@code function} to load keys, without supporting either
   * reloading or bulk loading. This allows creating a cache loader using a lambda expression.
   *
   * <p>The returned object is serializable if {@code function} is serializable.
   *
   * @param function the function to be used for loading values; must never return {@code null}

          V,
          I extends Table<R, C, V>>
      Collector<T, ?, I> toTable(
          java.util.function.Function<? super T, ? extends R> rowFunction,
          java.util.function.Function<? super T, ? extends C> columnFunction,
          java.util.function.Function<? super T, ? extends V> valueFunction,
          java.util.function.Supplier<I> tableSupplier) {
    return TableCollectors.<T, R, C, V, I>toTable(
        rowFunction,

  private static <T> void testSuccessfulForwarding(
      Class<T> interfaceType, Method method, Function<? super T, ? extends T> wrapperFunction) {
    new InteractionTester<T>(interfaceType, method).testInteraction(wrapperFunction);
  }

  private static <T> void testExceptionPropagation(
      Class<T> interfaceType, Method method, Function<? super T, ? extends T> wrapperFunction) {
    RuntimeException exception = new RuntimeException();