// Path: src/main/java/com/fernandocejas/arrow/functions/Function.java
// public interface Function<F, T> {
//   /**
//    * Returns the result of applying this function to {@code input}. This method is <i>generally
//    * expected</i>, but not absolutely required, to have the following properties:
//    *
//    * <ul>
//    * <li>Its execution does not cause any observable side effects.
//    * <li>The computation is <i>consistent with equals</i>.
//    * Objects.equal}{@code (a, b)} implies that {@code Objects.equal(function.apply(a),
//    * function.apply(b))}.
//    * </ul>
//    *
//    * @throws NullPointerException if {@code input} is null
//    */
//   @Nullable T apply(F input);
// 
//   /**
//    * Indicates whether another object is equal to this function.
//    *
//    * <p>Most implementations will have no reason to override the behavior of {@link Object#equals}.
//    * However, an implementation may also choose to return {@code true} whenever {@code object} is a
//    * {@link Function} that it considers <i>interchangeable</i> with this one. "Interchangeable"
//    * <i>typically</i> means that {@code Objects.equal(this.apply(f), that.apply(f))} is true for
//    * all
//    * {@code f} of type {@code F}. Note that a {@code false} result from this method does not imply
//    * that the functions are known <i>not</i> to be interchangeable.
//    */
//   @Override boolean equals(@Nullable Object object);
// }
// 
// Path: src/main/java/com/fernandocejas/arrow/checks/Preconditions.java
// public static <T> T checkNotNull(T reference) {
//   if (reference == null) {
//     throw new NullPointerException();
//   }
//   return reference;
// }


import com.fernandocejas.arrow.functions.Function;
import java.util.Collections;
import java.util.Set;
import org.jetbrains.annotations.Nullable;
import static com.fernandocejas.arrow.checks.Preconditions.checkNotNull;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    return (Optional<T>) checkNotNull(secondChoice);
  }

  @Override
  @Nullable
  public T orNull() {
    return null;
  }

  @Override
  public Set<T> asSet() {
    return Collections.emptySet();
  }

  @Override
// Path: src/main/java/com/fernandocejas/arrow/functions/Function.java
// public interface Function<F, T> {
//   /**
//    * Returns the result of applying this function to {@code input}. This method is <i>generally
//    * expected</i>, but not absolutely required, to have the following properties:
//    *
//    * <ul>
//    * <li>Its execution does not cause any observable side effects.
//    * <li>The computation is <i>consistent with equals</i>.
//    * Objects.equal}{@code (a, b)} implies that {@code Objects.equal(function.apply(a),
//    * function.apply(b))}.
//    * </ul>
//    *
//    * @throws NullPointerException if {@code input} is null
//    */
//   @Nullable T apply(F input);
// 
//   /**
//    * Indicates whether another object is equal to this function.
//    *
//    * <p>Most implementations will have no reason to override the behavior of {@link Object#equals}.
//    * However, an implementation may also choose to return {@code true} whenever {@code object} is a
//    * {@link Function} that it considers <i>interchangeable</i> with this one. "Interchangeable"
//    * <i>typically</i> means that {@code Objects.equal(this.apply(f), that.apply(f))} is true for
//    * all
//    * {@code f} of type {@code F}. Note that a {@code false} result from this method does not imply
//    * that the functions are known <i>not</i> to be interchangeable.
//    */
//   @Override boolean equals(@Nullable Object object);
// }
// 
// Path: src/main/java/com/fernandocejas/arrow/checks/Preconditions.java
// public static <T> T checkNotNull(T reference) {
//   if (reference == null) {
//     throw new NullPointerException();
//   }
//   return reference;
// }


// Path: src/main/java/com/fernandocejas/arrow/optional/Absent.java
import com.fernandocejas.arrow.functions.Function;
import java.util.Collections;
import java.util.Set;
import org.jetbrains.annotations.Nullable;
import static com.fernandocejas.arrow.checks.Preconditions.checkNotNull;

  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    return (Optional<T>) checkNotNull(secondChoice);
  }

  @Override
  @Nullable
  public T orNull() {
    return null;
  }

  @Override
  public Set<T> asSet() {
    return Collections.emptySet();
  }

  @Override
  public <V> Optional<V> transform(Function<? super T, V> function) {