### Top-level application { #top-level-application }

First, create the main, top-level, **FastAPI** application, and its *path operations*:

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[3, 6:8] *}

### Sub-application { #sub-application }

Then, create your sub-application, and its *path operations*.

	if err != nil {
		t.Fatalf("Failed to decode master key: %v", err)
	}
	KMS, err := kms.NewBuiltin("my-key", key)
	if err != nil {
		t.Fatalf("Failed to create KMS: %v", err)
	}

	for i, test := range encryptDecryptTests {
		ciphertext, err := Encrypt(KMS, bytes.NewReader(test.Data), test.Context)
		if err != nil {
			t.Fatalf("Test %d: failed to encrypt stream: %v", i, err)

    private static final String CRYPTO_ERROR_MESSAGE = "Unsupported cryptographic algorithm: AES-256-GCM";
    private static final String ALGORITHM_NAME = "AES-256-GCM";

    @Test
    @DisplayName("Default constructor should create exception with null message and cause")
    void testDefaultConstructor() {
        // Given & When
        CIFSUnsupportedCryptoException exception = new CIFSUnsupportedCryptoException();

        // Then

    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, summary="Create an item")
async def create_item(item: Item):
    """
    Create an item with all the information:

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required

    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, summary="Create an item")
async def create_item(item: Item):
    """
    Create an item with all the information:

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required

/**
 * Request body for creating mapping dictionary via REST API.
 * Extends CreateForm to inherit validation and field definitions.
 */
public class CreateBody extends CreateForm {

    /**
     * Creates a new CreateBody instance.
     */
    public CreateBody() {
    }

/**
 * Request body for creating group via REST API.
 * Extends CreateForm to inherit validation and field definitions.
 */
public class CreateBody extends CreateForm {

    /**
     * Creates a new CreateBody instance.
     */
    public CreateBody() {
    }

/**
 * Request body for creating access token via REST API.
 * Extends CreateForm to inherit validation and field definitions.
 */
public class CreateBody extends CreateForm {

    /**
     * Creates a new CreateBody instance.
     */
    public CreateBody() {
    }

/**
 * Request body for creating key match via REST API.
 * Extends CreateForm to inherit validation and field definitions.
 */
public class CreateBody extends CreateForm {

    /**
     * Creates a new CreateBody instance.
     */
    public CreateBody() {
    }

/**
 * Request body for creating search list via REST API.
 * Extends CreateForm to inherit validation and field definitions.
 */
public class CreateBody extends CreateForm {

    /**
     * Creates a new CreateBody instance.
     */
    public CreateBody() {
    }