content: package okreplay;
  
  import javax.annotation.Nullable;
  
  public interface Predicate<T> {
    /**
     * Returns the result of applying this predicate to {@code input} (Java 8 users, see notes in the
     * class documentation above). 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>; that is, {@link Objects#equal
     *     Objects.equal}{@code (a, b)} implies that {@code predicate.apply(a) ==
     *     predicate.apply(b))}.
     * </ul>
     *
     * @throws NullPointerException if {@code input} is null and this predicate does not accept null
     *     arguments
     */
    boolean apply(@Nullable T input);
  
    /**
     * Indicates whether another object is equal to this predicate.
     *
     * <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 Predicate} that it considers <i>interchangeable</i> with this one. "Interchangeable"
     * <i>typically</i> means that {@code this.apply(t) == that.apply(t)} for all {@code t} of type
     * {@code T}). Note that a {@code false} result from this method does not imply that the
     * predicates are known <i>not</i> to be interchangeable.
     */
    @Override
    boolean equals(@Nullable Object object);
  }