} while (oldHead != Waiter.TOMBSTONE);
      }
      // re-read valueField, if we get here then we must have observed a TOMBSTONE while trying to
      // add a waiter.
      // requireNonNull is safe because valueField is always set before TOMBSTONE.
      return getDoneValue(requireNonNull(valueField));
    }
    // If we get here then we have remainingNanos < SPIN_THRESHOLD_NANOS and there is no node on the
    // waiters list

## Be Nice

First of all, be nice. 😊

You probably are super nice if you were added to the team, but it's worth mentioning it. 🤓

### When Things are Difficult

When things are great, everything is easier, so that doesn't need much instructions. But when things are difficult, here are some guidelines.

     * If the given {@code paths} argument contains no element, then this method returns an empty string.
     *
     * <h4>Examples</h4>
     * If {@code paths} is a list containing two elements, {@code dir/path1} and {@code dir/path2}, then:
     *
     * <ul>
     *   <li>If this type is {@link JavaPathType#MODULES}, then this method returns
     *       {@code {"--module-path", "dir/path1:dir/path2"}} on Unix or

Being able to use asynchronous functions in your tests could be useful, for example, when you're querying your database asynchronously. Imagine you want to test sending requests to your FastAPI application and then verify that your backend successfully wrote the correct data in the database, while using an async database library.

Let's look at how we can make that work.

    checkHelperVersion(NO_ATOMIC_REFERENCE_FIELD_UPDATER, "SynchronizedHelper");

    // Then, run the actual tests under each alternative classloader:

    /*
     * We don't need to test further under NO_UNSAFE: We verified that it selects
     * AtomicReferenceFieldUpdaterAtomicHelper, which is the default, which means that it's used
     * when we run AbstractFutureTest itself.
     */

    /*

         * where this isn't true, but we ignore it: If we record an exception, then someone calls
         * initCause() on it, and then we examine it again, we'll conclude that we've seen the whole
         * chain before when in fact we haven't. But this should be rare.)
         */
        return false;
      }
    }
    return true;
  }

And then, that system (in this case **FastAPI**) will take care of doing whatever is needed to provide your code with those needed dependencies ("inject" the dependencies).

This is very useful when you need to:

* Have shared logic (the same code logic again and again).
* Share database connections.

   * safe range. If {@code safeMax < safeMin} then no code points are considered safe. This
   * initializer is useful when explicit instances of ArrayBasedEscaperMap are used to allow the
   * sharing of large replacement mappings.
   *
   * <p>If a code point has no mapped replacement then it is checked against the safe range. If it
   * lies outside that, then {@link #escapeUnsafe} is called, otherwise no escaping is performed.
   *

The `root_path` is used to handle these specific cases.

And it's also used internally when mounting sub-applications.

Having a proxy with a stripped path prefix, in this case, means that you could declare a path at `/app` in your code, but then, you add a layer on top (the proxy) that would put your **FastAPI** application under a path like `/api/v1`.

   * is not guaranteed to return zero when the dataset consists of the same pair of values multiple
   * times, due to numerical errors.
   *
   * <h3>Non-finite values</h3>
   *
   * <p>If the dataset contains any non-finite values ({@link Double#POSITIVE_INFINITY}, {@link
   * Double#NEGATIVE_INFINITY}, or {@link Double#NaN}) then the result is {@link Double#NaN}.
   *