*/
    public static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

    /**
     * This is an alternative to the <code>java.lang.Integer.toHexString</code>
     * method. It is an efficient relative that also will pad the left side so
     * that the result is <code>size</code> digits.
     *

It is imported/included directly into FastAPI so that you can import it from `fastapi` and avoid accidentally importing the alternative `BackgroundTask` (without the `s` at the end) from `starlette.background`.

        Cell a = as[i];
        if (a != null) sum += a.value;
      }
    }
    return sum;
  }

  /**
   * Resets variables maintaining the sum to zero. This method may be a useful alternative to
   * creating a new adder, but is only effective if there are no concurrent updates. Because this
   * method is intrinsically racy, it should only be used when it is known that no threads are
   * concurrently updating.

    checkHelperVersion(NO_UNSAFE, "AtomicReferenceFieldUpdaterAtomicHelper");
    checkHelperVersion(NO_ATOMIC_REFERENCE_FIELD_UPDATER, "SynchronizedHelper");

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

    /*
     * Under Java 8, there is no need to test the no-VarHandle case here: It's already tested by the
     * main AbstractFutureTest, which uses the default AtomicHelper, which we verified above to be

```

////

//// tab | Python 3.9+

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009_py39.py!}
```

////

//// tab | Python 3.9+ Alternative

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009b_py39.py!}
```

////

#### `Union` oder `Optional` verwenden? { #using-union-or-optional }

* Show a **clear error** for the client when the data is not valid
* **Document** the parameter in the OpenAPI schema *path operation* (so it will show up in the **automatic docs UI**)

## Alternative (old): `Query` as the default value { #alternative-old-query-as-the-default-value }

    override fun close() {
      if (closed) return
      closed = true
      detachTimeout(timeout)
      state = STATE_READ_RESPONSE_HEADERS
    }
  }

  /**
   * An HTTP body with alternating chunk sizes and chunk bodies. It is the caller's responsibility
   * to buffer chunks; typically by using a buffered sink with this sink.
   */
  private inner class ChunkedSink : Sink {

* Den Parameter in der OpenAPI-Schema-*Pfadoperation* **dokumentieren** (sodass er in der **automatischen Dokumentation** angezeigt wird)

## Alternative (alt): `Query` als Defaultwert { #alternative-old-query-as-the-default-value }

 * lifecycle phase. Standard lifecycles use plugin execution {@code <phase>} or mojo default lifecycle phase to
 * calculate the execution plan, but custom lifecycles can use alternative mapping strategies.
 */
@Named(DefaultLifecycleMappingDelegate.HINT)
@Singleton
public class DefaultLifecycleMappingDelegate implements LifecycleMappingDelegate {
    public static final String HINT = "default";

    if (it.length < 2) {
      "0$it"
    } else {
      it
    }
  }

internal fun commonHeadersOf(vararg inputNamesAndValues: String): Headers {
  require(inputNamesAndValues.size % 2 == 0) { "Expected alternating header names and values" }

  // Make a defensive copy and clean it up.
  val namesAndValues: Array<String> = arrayOf(*inputNamesAndValues)
  for (i in namesAndValues.indices) {