///

---

Si estás usando un paquete de terceros que se comunica con algo (una base de datos, una API, el sistema de archivos, etc.) y no tiene soporte para usar `await` (este es actualmente el caso para la mayoría de los paquetes de base de datos), entonces declara tus *path operation functions* como normalmente, usando simplemente `def`, así:

```Python hl_lines="2"
@app.get('/')
def results():

        for (int i = 0; i < 8; i++) {
            tail[padLen + i] = (byte) (count * 8 >>> 8 * i);
        }

        engineUpdate(tail, 0, tail.length);

        final byte[] result = new byte[16];
        // cast this MD4's context (array of 4 ints) into an array of 16 bytes.
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                result[i * 4 + j] = (byte) (context[i] >>> 8 * j);
            }

import okio.ByteString

/**
 * ASN.1 adapters adapted from the specifications in [RFC 5280][rfc_5280].
 *
 * [rfc_5280]: https://tools.ietf.org/html/rfc5280
 */
@Suppress("UNCHECKED_CAST") // This needs to cast decoded collections.
internal object CertificateAdapters {
  /**
   * ```
   * Time ::= CHOICE {
   *   utcTime        UTCTime,
   *   generalTime    GeneralizedTime
   * }
   * ```
   *

   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(type::isInstance).map(type::cast)}.
   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * {@snippet :
   * @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =

                  for (Field f : k.getDeclaredFields()) {
                    f.setAccessible(true);
                    Object x = f.get(null);
                    if (k.isInstance(x)) {
                      return k.cast(x);
                    }
                  }
                  throw new NoSuchFieldError("the Unsafe");
                });
      } catch (PrivilegedActionException e) {

    assertCastFails(Long.MAX_VALUE);
    assertCastFails(Long.MIN_VALUE);
  }

  private static void assertCastFails(long value) {
    try {
      UnsignedInts.checkedCast(value);
      fail("Cast to int should have failed: " + value);
    } catch (IllegalArgumentException ex) {
      assertThat(ex).hasMessageThat().contains(String.valueOf(value));
    }
  }

  public void testSaturatedCast() {

from contextlib import AsyncExitStack, contextmanager
from copy import copy, deepcopy
from dataclasses import dataclass
from typing import (
    Annotated,
    Any,
    ForwardRef,
    Literal,
    Union,
    cast,
    get_args,
    get_origin,
)

from fastapi import params
from fastapi._compat import (
    ModelField,
    RequiredParam,
    Undefined,
    copy_field_info,
    create_body_model,

    }

    @Override
    public K[] createArray(int length) {
      // TODO: with appropriate refactoring of OneSizeGenerator, we can perhaps
      // tidy this up and get rid of the casts here and in
      // MapValueCollectionGenerator.

      return ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createKeyArray(length);
    }

    @Override

        return o != null;
      }

      @Override
      public String toString() {
        return "Predicates.notNull()";
      }
    };

    @SuppressWarnings("unchecked") // safe contravariant cast
    <T extends @Nullable Object> Predicate<T> withNarrowedType() {
      return (Predicate<T>) this;
    }
  }

  /**
   * @see Predicates#not(Predicate)
   */

```Python hl_lines="1"
@router.get("/{item_id}")
async def read_item(item_id: str):
    ...
```

...el prefijo no debe incluir un `/` final.

Así que, el prefijo en este caso es `/items`.

También podemos agregar una lista de `tags` y `responses` extra que se aplicarán a todas las *path operations* incluidas en este router.