### Short

It has sensible **defaults** for everything, with optional configurations everywhere. All the parameters can be fine-tuned to do what you need and to define the API you need.

But by default, it all **"just works"**.

### Validation

* Validation for most (or all?) Python **data types**, including:
    * JSON objects (`dict`).

    // vol. 2, Knuth, 4.2.2, (16) to the two-variable case. We have two value series x_i and y_i.
    // We define the arithmetic means X_n = 1/n \sum_{i=1}^n x_i, and Y_n = 1/n \sum_{i=1}^n y_i.
    // We also define the sum of the products of the differences from the means
    //           C_n = \sum_{i=1}^n x_i y_i - n X_n Y_n
    // for all n >= 1. Then for all n > 1:

Das ist keine Limitation von **FastAPI**, sondern Teil des HTTP-Protokolls.

///

## Optionaler Datei-Upload

Sie können eine Datei optional machen, indem Sie Standard-Typannotationen verwenden und den Defaultwert auf `None` setzen:

//// tab | Python 3.10+

* **Coroutines**

## Código Asíncrono

El código asíncrono sólo significa que el lenguaje 💬 tiene una manera de decirle al sistema / programa 🤖 que, en algún momento del código, 🤖 tendrá que esperar a que *algo más* termine en otro sitio. Digamos que ese *algo más* se llama, por ejemplo, "archivo lento" 📝.

Durante ese tiempo, el sistema puede hacer otras cosas, mientras "archivo lento" 📝 termina.

```
KEY:
storage_class  define object level redundancy

ARGS:
standard  (string)    set the parity count for default standard storage class e.g. "EC:4"
rrs       (string)    set the parity count for reduced redundancy storage class e.g. "EC:2"
comment   (sentence)  optionally add a comment to this setting
```

or environment variables

```
KEY:
storage_class  define object level redundancy

ARGS:

      return emptySet();
    }
  }

  /**
   * Creates a suite whose map has some elements filtered out of view.
   *
   * <p>Because the map may be ascending or descending, this test must derive the relative order of
   * these extreme values rather than relying on their regular sort ordering.
   */
  final TestSuite createSubmapSuite(
      FeatureSpecificTestSuiteBuilder<

 * to be the last step of the pipeline.
 *
 * <h4>Transforming</h4>
 *
 * To derive the next step by asynchronously applying a function to an input step's value, call
 * {@link #transform(ClosingFunction, Executor)} or {@link #transformAsync(AsyncClosingFunction,
 * Executor)} on the input step.
 *
 * <h4>Catching</h4>
 *
 * To derive the next step from a failed input step, call {@link #catching(Class, ClosingFunction,

      assertTaskWrapped(tasks);
      lastMethodCalled = "invokeAllTimeout";
      lastTimeoutInMillis = unit.toMillis(timeout);
      return inline.invokeAll(tasks, timeout, unit);
    }

    // Define the invokeAny methods to invoke the first task
    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
        throws ExecutionException, InterruptedException {
      assertTaskWrapped(tasks);

    <suppress checks="JavadocPackage"
              files=".*[/\\]platforms[/\\]ide[/\\]ide-plugins[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]plugins[/\\]ide[/\\]eclipse[/\\][^/\\]+"/>

    <!-- Protocol types may only define constants in interfaces -->
    <suppress checks="InterfaceIsTypeCheck"
              files=".*[/\\]tooling-api[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]tooling[/\\]internal[/\\]protocol.+"/>

///

Here we define the config `env_file` inside of your Pydantic `Settings` class, and set the value to the filename with the dotenv file we want to use.

### Creating the `Settings` only once with `lru_cache`