```

Notice that the default value is still `None`, so the parameter is still optional.

But now, having `Query(max_length=50)` inside of `Annotated`, we are telling FastAPI that we want it to extract this value from the query parameters (this would have been the default anyway 🤷) and that we want to have **additional validation** for this value (that's why we do this, to get the additional validation). 😎

code is a library, we strongly recommend using the [Guava Beta Checker] to
ensure that you do not use any `@Beta` APIs!**

[Guava Beta Checker]: https://github.com/google/guava-beta-checker

<!-- References -->

 * iterator} method only once, and should be tested using this class. Exceptions to this rule should
 * be clearly documented.
 *
 * <p>Note that although your APIs should be liberal in what they accept, your methods which
 * <i>return</i> iterables should make every attempt to return ones of the robust variety.
 *
 * <p>This testing utility is not thread-safe.
 *
 * @author Kevin Bourrillion

final class SortedLists {
  private SortedLists() {}

  /**
   * A specification for which index to return if the list contains at least one element that
   * compares as equal to the key.
   */
  enum KeyPresentBehavior {
    /**
     * Return the index of any list element that compares as equal to the key. No guarantees are
     * made as to which index is returned, if more than one element compares as equal to the key.
     */

  }

  /**
   * Returns the {@link Method} instance for {@link #testAddAll_unsupportedNonePresent()} so that
   * tests can suppress it with {@code FeatureSpecificTestSuiteBuilder.suppressing()} while we
   * figure out what to do with <a href="http://goo.gl/qJBruX">{@code ConcurrentHashMap} support for
   * {@code entrySet().add()}</a>.
   */
  @J2ktIncompatible

And adding type hints normally doesn't change what happens from what would happen without them.

But now, imagine you are again in the middle of creating that function, but with type hints.

At the same point, you try to trigger the autocomplete with `Ctrl+Space` and you see:

<img src="/img/python-types/image02.png">

With that, you can scroll, seeing the options, until you find the one that "rings a bell":

   * It's unclear whether nulls were to be permitted or forbidden, but presumably the eventual fix
   * will be to permit them, as it seems more likely that code would depend on that behavior than on
   * the other. Thus, we say the bug is in add(), which fails to support null.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static Method getAddNullSupportedMethod() {

public class AbstractListTester<E extends @Nullable Object> extends AbstractCollectionTester<E> {
  /*
   * Previously we had a field named list that was initialized to the value of
   * collection in setUp(), but that caused problems when a tester changed the
   * value of list or collection but not both.
   */
  protected final List<E> getList() {
    return (List<E>) collection;
  }

  /**

This way, you don't have to know beforehand what the valid field/attribute names are (as would be the case with Pydantic models).

This would be useful if you want to receive keys that you don't already know.

---

Another useful case is when you want to have keys of another type (e.g., `int`).

That's what we are going to see here.

  // DriverName defines the name of the dynamic resource driver that is
  // used for allocation of a ResourceClaim that uses this class.
  //
  // Resource drivers have a unique name in forward domain order
  // (acme.example.com).
  optional string driverName = 2;

  // ParametersRef references an arbitrary separate object that may hold
  // parameters that will be used by the driver when allocating a