boolean usesFastPath();
  }

  /**
   * The only reference to Unsafe is in this nested class. We set things up so that if
   * Unsafe.theUnsafe is inaccessible, the attempt to load the nested class fails, and the outer
   * class's static initializer can fall back on a non-Unsafe version.
   */
  @SuppressWarnings("SunApi") // b/345822163
  @VisibleForTesting

      method.invoke(null, ClosingFuture.class); // to make sure the method is accessible
      return true;
    } catch (NoSuchMethodException | IllegalAccessException probablyBeforeJava9OrAndroid28) {
      /*
       * It's theoretically possible for Reference.reachabilityFence to exist under older VMs in an
       * inaccessible form.
       */
      return false;
    } catch (InvocationTargetException e) {

   *     default value of a parameter cannot be determined.
   * @throws IllegalAccessException if the class isn't public or is nested inside a non-public
   *     class, preventing its methods from being accessible.
   * @throws InvocationTargetException if a static method threw exception.
   */
  private <T> @Nullable T instantiate(Invokable<?, ? extends T> factory)

*  In the `keras` PyPI package, accessible symbols are now restricted to symbols that are intended to be public. This may affect your code if you were using `import keras` and you used `keras` functions that were not public APIs, but were accessible in earlier versions with direct imports. In those cases, please use the following guideline:

Function literals are <i>closures</i>: they may refer to variables
declared in a surrounding function. Those variables are then shared between
the surrounding function and the function literal, and they survive as long
as they are accessible.
</p>


<h3 id="Primary_expressions">Primary expressions</h3>

<p>
Primary expressions are the operands for unary and binary expressions.
</p>

<pre class="ebnf">