public interface Option<T> {
  T get();
  boolean isDefined();
}

public class Some<T> implements Option<T> {
  private final T value;

  public Some(T value) {
    this.value = value;
  }

  public boolean isDefined() {
    return false;
  }

  public T get() {
    return value;
  }
}

public final class None<T> implements Option<T> {
  public None() {
  }

  public boolean isDefined() {
    return true;
  }

  public T get() {
    throw new UnsupportedOperationException("Cannot resolve value on None");
  }
}