### Write your own async code { #write-your-own-async-code }

Starlette (and **FastAPI**) are based on [AnyIO](https://anyio.readthedocs.io/en/stable/), which makes it compatible with both Python's standard library [asyncio](https://docs.python.org/3/library/asyncio-task.html) and [Trio](https://trio.readthedocs.io/en/stable/).

    //   4 bytes for the array length
    return (bits.bitSize() / 8) + 6;
  }

  /**
   * Determines whether a given Bloom filter is compatible with this Bloom filter. For two Bloom
   * filters to be compatible, they must:
   *
   * <ul>
   *   <li>not be the same instance
   *   <li>have the same number of hash functions
   *   <li>have the same bit size

        if (utf8Length != Utf8.encodedLength(sb)) {
          StringBuilder repro = new StringBuilder();
          for (int j = 0; j < sb.length(); j++) {
            repro.append(" ").append((int) sb.charAt(j)); // GWT compatible
          }
          assertEquals(repro.toString(), utf8Length, Utf8.encodedLength(sb));
        }
      }
    }
  }

  public void testEncodedLength_invalidStrings() {

if ERRORLEVEL 1 (
    echo Error: Apache Maven 4.x requires Java 17 or newer to run. >&2
    "%JAVACMD%" -version >&2
    echo Please upgrade your Java installation or set JAVA_HOME to point to a compatible JDK. >&2
    goto error
)

:chkMHome
set "MAVEN_HOME=%~dp0"
set "MAVEN_HOME=%MAVEN_HOME:~0,-5%"
if "%MAVEN_HOME%"=="" goto error

:checkMCmd
if not exist "%MAVEN_HOME%\bin\mvn.cmd" goto error

	// SSEDAREPackageMetaSize - SSE dare package meta padding bytes.
	SSEDAREPackageMetaSize = 32 // 32 bytes

)

// KMSKeyID returns in AWS compatible KMS KeyID() format.
func (o *ObjectInfo) KMSKeyID() string { return kmsKeyIDFromMetadata(o.UserDefined) }

// KMSKeyID returns in AWS compatible KMS KeyID() format.
func (o *MultipartInfo) KMSKeyID() string { return kmsKeyIDFromMetadata(o.UserDefined) }

    // It would be nice to be able to return a real concurrent
    // collection like ConcurrentLinkedQueue, so that e.g. concurrent
    // iteration would work, but that would not be GWT-compatible.
    // We are not "just" inheriting from ArrayList here as this doesn't work for J2kt.
    return new AbstractList<T>() {
      final ArrayList<T> data = new ArrayList<>();

      @Override

            model = model.withDependencies(null).withPackaging(POM_PACKAGING);
        }
        if (!preserveModelVersion) {
            /*
             * If the <build> contains <source> elements, it is not compatible with the Maven 4.0.0 model.
             * Remove the full <build> element instead of removing only the <sources> element, because the

	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	getObjectInfo := objectAPI.GetObjectInfo

	// Check for auth type to return S3 compatible error.
	// type to return the correct error (NoSuchKey vs AccessDenied)
	if s3Error := checkRequestAuthType(ctx, r, policy.GetObjectAction, bucket, zipPath); s3Error != ErrNone {
		if getRequestAuthType(r) == authTypeAnonymous {

        assertTrue(transport.isSigningOptional());
        assertTrue(transport.isSigningEnforced());
    }

    @Test
    @DisplayName("unwrap returns this for compatible types and throws otherwise")
    void unwrapBehavior() {
        // Happy paths
        SmbTransport asIface = transport.unwrap(SmbTransport.class);
        assertSame(transport, asIface);

Si declaras un [Response Model](../tutorial/response-model.md) FastAPI lo usará para serializar los datos a JSON, usando Pydantic.

Si no declaras un response model, FastAPI usará el `jsonable_encoder` explicado en [Codificador Compatible con JSON](../tutorial/encoder.md) y lo pondrá en un `JSONResponse`.