this.singleValue = value;
    this.inverse = inverse;
  }

  @Override
  public ImmutableBiMap<V, K> inverse() {
    ImmutableBiMap<V, K> result = inverse;
    if (result == null) {
      return inverse = new SingletonImmutableBiMap<V, K>(singleValue, singleKey, this);
    } else {
      return result;
    }
  }

  @Override
  public ImmutableSet<V> values() {
    return ImmutableSet.of(singleValue);
  }

  public abstract double transform(double x);

  /**
   * Returns the inverse linear transformation. The inverse of a horizontal transformation is a
   * vertical transformation, and vice versa. The inverse of the {@link #forNaN} transformation is
   * itself. In all other cases, the inverse is a transformation such that applying both the
   * original transformation and its inverse to a value gives you the original value give-or-take

        .inOrder();
    // backward map ordered by country
    assertThat(bimap.inverse().keySet())
        .containsExactly(Country.CANADA, Country.CHILE, Country.SWITZERLAND)
        .inOrder();
    // backward map ordered by country (even for currency values)
    assertThat(bimap.inverse().values())
        .containsExactly(Currency.DOLLAR, Currency.PESO, Currency.FRANC)
        .inOrder();
  }

    }
    ImmutableMap<V, K> backwardMap = builder.build();
    this.inverse = new RegularImmutableBiMap<V, K>(backwardMap, this);
  }

  RegularImmutableBiMap(ImmutableMap<K, V> delegate, ImmutableBiMap<V, K> inverse) {
    super(delegate);
    this.inverse = inverse;
  }

  @Override
  public ImmutableBiMap<V, K> inverse() {
    return inverse;
  }

    this.singleKey = singleKey;
    this.singleValue = singleValue;
    this.inverse = null;
  }

  private SingletonImmutableBiMap(K singleKey, V singleValue, ImmutableBiMap<V, K> inverse) {
    this.singleKey = singleKey;
    this.singleValue = singleValue;
    this.inverse = inverse;
  }

  @Override
  public @Nullable V get(@Nullable Object key) {

import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for the {@code inverse} view of a BiMap.
 *
 * <p>This assumes that {@code bimap.inverse().inverse() == bimap}, which is not technically
 * required but is fulfilled by all current implementations.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

  /**
   * Returns the inverse view of this bimap, which maps each of this bimap's values to its
   * associated key. The two bimaps are backed by the same data; any changes to one will appear in
   * the other.
   *
   * <p><b>Note:</b> There is no guaranteed correspondence between the iteration order of a bimap
   * and that of its inverse.
   *
   * @return the inverse view of this bimap
   */

    assertEquals("dollar", bimap.get("canada"));
    assertEquals("canada", bimap.inverse().get("dollar"));
  }

  private static final int N = 1000;

  public void testBashIt() throws Exception {
    BiMap<Integer, Integer> bimap = HashBiMap.create(N);
    BiMap<Integer, Integer> inverse = bimap.inverse();

    for (int i = 0; i < N; i++) {
      assertNull(bimap.put(2 * i, 2 * i + 1));
    }

import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for the {@code inverse} view of a BiMap.
 *
 * <p>This assumes that {@code bimap.inverse().inverse() == bimap}, which is not technically
 * required but is fulfilled by all current implementations.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

    assertEquals("one", copy.inverse().get(1));
    assertSame(copy, copy.inverse().inverse());
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testInverseSerialization() {
    ImmutableBiMap<String, Integer> bimap =
        ImmutableBiMap.copyOf(ImmutableMap.of(1, "one", 2, "two")).inverse();