*       interrupt).
   *   <li>Any {@link CancellationException} is propagated untouched, as is any other {@link
   *       RuntimeException} (though {@code get} implementations are discouraged from throwing such
   *       exceptions).
   * </ul>
   *
   * <p>The overall principle is to continue to treat every checked exception as a checked

      return o.toString();
    }

    @Override
    public String toString() {
      return "Functions.toStringFunction()";
    }
  }

  /**
   * Returns the identity function.
   *
   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
   * more readable.
   */
  // implementation is "fully variant"; E has become a "pass-through" type
  @SuppressWarnings("unchecked")

    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**
   * Returns a supplier that always supplies {@code instance}.
   *
   * <p><b>Discouraged:</b> Prefer using {@code () -> instance}, but note that lambdas do not have
   * human-readable {@link #toString()} representations and are not serializable. If you need a

   *
   * @throws IllegalStateException if the instance is absent ({@link #isPresent} returns {@code
   *     false}); depending on this <i>specific</i> exception type (over the more general {@link
   *     RuntimeException}) is discouraged
   */
  public abstract T get();

  /**
   * Returns the contained instance if it is present; {@code defaultValue} otherwise. If no default

    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**
   * Returns a supplier that always supplies {@code instance}.
   *
   * <p><b>Discouraged:</b> Prefer using {@code () -> instance}, but note that lambdas do not have
   * human-readable {@link #toString()} representations and are not serializable. If you need a

      return o.toString();
    }

    @Override
    public String toString() {
      return "Functions.toStringFunction()";
    }
  }

  /**
   * Returns the identity function.
   *
   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
   * more readable.
   */
  // implementation is "fully variant"; E has become a "pass-through" type
  @SuppressWarnings("unchecked")

 *       recommend using our {@link VerifyException} exception type. Throwing a plain {@link
 *       RuntimeException} is frowned upon.
 *   <li>Use of {@link java.util.Objects#requireNonNull(Object)} is generally discouraged, since
 *       {@link #verifyNotNull(Object)} and {@link Preconditions#checkNotNull(Object)} perform the
 *       same function with more clarity.
 * </ul>
 *
 * <h3>Warning about performance</h3>
 *

   *
   * @throws IllegalStateException if the instance is absent ({@link #isPresent} returns {@code
   *     false}); depending on this <i>specific</i> exception type (over the more general {@link
   *     RuntimeException}) is discouraged
   */
  public abstract T get();

  /**
   * Returns the contained instance if it is present; {@code defaultValue} otherwise. If no default

    }
  }

  /**
   * Propagates {@code throwable} exactly as-is, if and only if it is an instance of {@link
   * RuntimeException}, {@link Error}, or {@code declaredType}.
   *
   * <p><b>Discouraged</b> in favor of calling {@link #throwIfInstanceOf} and {@link
   * #throwIfUnchecked}.
   *
   * @param throwable the Throwable to possibly propagate

 *       recommend using our {@link VerifyException} exception type. Throwing a plain {@link
 *       RuntimeException} is frowned upon.
 *   <li>Use of {@link java.util.Objects#requireNonNull(Object)} is generally discouraged, since
 *       {@link #verifyNotNull(Object)} and {@link Preconditions#checkNotNull(Object)} perform the
 *       same function with more clarity.
 * </ul>
 *
 * <h3>Warning about performance</h3>
 *