return set1.contains(element) ^ set2.contains(element);
      }

      @Override
      int minSize() {
        int difference = minSize(set1) - maxSize(set2);
        return difference >= 0 ? difference : max(minSize(set2) - maxSize(set1), 0);
      }

      @Override
      int maxSize() {
        return saturatedAdd(maxSize(set1), maxSize(set2));
      }

//   example, one cannot use the output of "switch" node as input.
// - `inputs` and `outputs` cannot have reference types. Reference types are
//   not exposed through C API and are being replaced with Resources. We support
//   reference types inside function's body to support legacy code. Do not
//   use them in new code.
// - Every node in the function's body must have all of its inputs (including

  }

  @SuppressWarnings("JUnitIncompatibleType")
  public void testWhere() {
    assertEquals(new TypeToken<Map<String, Integer>>() {}, mapOf(String.class, Integer.class));
    // Type inference is doomed here: int.class is the same as Integer.class, so this is comparing
    // TypeToken<int[]> and TypeToken<Integer[]>.
    assertEquals(new TypeToken<int[]>() {}, arrayOf(int.class));

  }

  @SuppressWarnings("JUnitIncompatibleType")
  public void testWhere() {
    assertEquals(new TypeToken<Map<String, Integer>>() {}, mapOf(String.class, Integer.class));
    // Type inference is doomed here: int.class is the same as Integer.class, so this is comparing
    // TypeToken<int[]> and TypeToken<Integer[]>.
    assertEquals(new TypeToken<int[]>() {}, arrayOf(int.class));

    if (reference == null) {
      throw new NullPointerException();
    }
    return reference;
  }

  /**
   * Ensures that an object reference passed as a parameter to the calling method is not null.
   *
   * @param reference an object reference
   * @param errorMessage the exception message to use if the check fails; will be converted to a

  /*
   * We avoid using a method reference or lambda here for now:
   *
   * - method reference: Inside Google, CacheBuilder is used from the implementation of a custom
   *   ClassLoader that is sometimes used as a system classloader. That's a problem because
   *   method-reference linking tries to look up the system classloader, and it fails because there
   *   isn't one yet.
   *

Config(t){if("object"==typeof(t=super._getConfig(t)).reference&&!l(t.reference)&&"function"!=typeof t.reference.getBoundingClientRect)throw new TypeError(`${pt.toUpperCase()}: Option "reference" provided type "object" without a required "getBoundingClientRect" method.`);return t}_createPopper(){if(void 0===s)throw new TypeError("Bootstrap's dropdowns require Popper (https://popper.js.org)");let t=this._element;"parent"===this._config.reference?t=this._parent:l(this._config.reference)?t=c(this._c...

     * the type of the concrete implementation.
     */
    abstract S self();

    /** Drains the reference queues used by this segment, if any. */
    @GuardedBy("this")
    void maybeDrainReferenceQueues() {}

    /** Clears the reference queues used by this segment, if any. */
    void maybeClearReferenceQueues() {}

    /** Sets the value of the given {@code entry}. */

nNavbar&&e){if("undefined"==typeof a.default)throw new TypeError("Bootstrap's dropdowns require Popper (https://popper.js.org)");var l=this._element;"parent"===this._config.reference?l=s:d.isElement(this._config.reference)&&(l=this._config.reference,"undefined"!=typeof this._config.reference.jquery&&(l=this._config.reference[0])),"scrollParent"!==this._config.boundary&&o.default(s).addClass("position-static"),this._popper=new a.default(l,this._menu,this._getPopperConfig())}"ontouchstart"in docum...

     * Another way to express this signature would be to bound <V> by @NonNull and accept
     * LF<? extends @Nullable V>. That might be better: There's currently no difference between the
     * outputs users get when calling this with <Foo> and calling it with <@Nullable Foo>. The only
     * difference is that calling it with <Foo> won't work when an input Future has a @Nullable
     * type. So why even make that error possible by giving callers the choice?