Let's say you have a file structure like this:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers
│   │   ├── __init__.py
│   │   ├── items.py
│   │   └── users.py
│   └── internal
│       ├── __init__.py
│       └── admin.py
```

/// tip

There are several `__init__.py` files: one in each directory or subdirectory.

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

The file `main.py` would have:

{* ../../docs_src/async_tests/main.py *}

The file `test_main.py` would have the tests for `main.py`, it could look like this now:

{* ../../docs_src/async_tests/test_main.py *}

## Run it { #run-it }

You can run your tests as usual via:

For example, you could have a file `config.py` with:

{* ../../docs_src/settings/app01/config.py *}

And then use it in a file `main.py`:

{* ../../docs_src/settings/app01/main.py hl[3,11:13] *}

/// tip

You would also need a file `__init__.py` as you saw in [Bigger Applications - Multiple Files](../tutorial/bigger-applications.md){.internal-link target=_blank}.

## Add regular expressions { #add-regular-expressions }

You can define a <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">regular expression</abbr> `pattern` that the parameter should match:

{* ../../docs_src/query_params_str_validations/tutorial004_an_py310.py hl[11] *}

    }

    // Test filename setter
    public void test_filename() {
        assertNull(pythonJob.filename);

        PythonJob result = pythonJob.filename("test.py");

        assertSame(pythonJob, result);
        assertEquals("test.py", pythonJob.filename);
    }

    // Test single argument addition
    public void test_arg() {
        assertTrue(pythonJob.argList.isEmpty());

**FastAPI** supports that the same way as with plain strings:

{* ../../docs_src/path_operation_configuration/tutorial002b.py hl[1,8:10,13,18] *}

## Summary and description { #summary-and-description }

You can add a `summary` and `description`:

{* ../../docs_src/path_operation_configuration/tutorial003_py310.py hl[18:19] *}

## Description from docstring { #description-from-docstring }

{* ../../docs_src/path_params/tutorial003.py hl[6,11] *}

Sebaliknya, path `/users/{user_id}` juga akan sesuai dengan `/users/me`, "menganggap" menerima parameter `user_id` dengan nilai `"me"`.

Serupa, anda juga tidak bisa mendefinisikan operasi path:

{* ../../docs_src/path_params/tutorial003b.py hl[6,11] *}

Path pertama akan selalu digunakan karena path sesuai dengan yang pertama.

///

{* ../../docs_src/path_params_numeric_validations/tutorial002.py hl[7] *}

////

But keep in mind that if you use `Annotated`, you won't have this problem, it won't matter as you're not using the function parameter default values for `Query()` or `Path()`.

{* ../../docs_src/path_params_numeric_validations/tutorial002_an_py39.py *}

## Order the parameters as you need, tricks { #order-the-parameters-as-you-need-tricks }

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009.py!}
```

////

//// tab | Python 3.8+ alternative

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009b.py!}
```

////

{* ../../docs_src/response_model/tutorial003_py310.py hl[9,11,16] *}

Here, even though our *path operation function* is returning the same input user that contains the password:

{* ../../docs_src/response_model/tutorial003_py310.py hl[24] *}

...we declared the `response_model` to be our model `UserOut`, that doesn't include the password:

{* ../../docs_src/response_model/tutorial003_py310.py hl[22] *}