# Debugging

You can connect the debugger in your editor, for example with Visual Studio Code or PyCharm.

## Call `uvicorn`

In your FastAPI application, import and run `uvicorn` directly:

```Python hl_lines="1  15"
{!../../docs_src/debugging/tutorial001.py!}
```

### About `__name__ == "__main__"`

The main purpose of the `__name__ == "__main__"` is to have some code that is executed when your file is called with:

License: Apache-2.0
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 .
 http://www.apache.org/licenses/LICENSE-2.0
 .
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,

**FastAPI** will **extract** the data for **each field** from the **cookies** received in the request and give you the Pydantic model you defined.

## Check the Docs

You can see the defined cookies in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/cookie-param-models/image01.png">
</div>

/// info

// Copyright Istio Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,

///

## Benutzerdefinierte Header hinzufügen

Es gibt Situationen, da ist es nützlich, dem HTTP-Error benutzerdefinierte Header hinzufügen zu können, etwa in einigen Sicherheitsszenarien.

Sie müssen das wahrscheinlich nicht direkt in ihrem Code verwenden.

Aber falls es in einem fortgeschrittenen Szenario notwendig ist, können Sie benutzerdefinierte Header wie folgt hinzufügen:

```Python hl_lines="14"

You can also declare the `Response` parameter in dependencies, and set headers (and cookies) in them.

## Return a `Response` directly

You can also add headers when you return a `Response` directly.

            async with anyio.create_task_group() as tg:
                for sub_value in value:
                    tg.start_soon(process_fn, sub_value.read)
            value = serialize_sequence_value(field=field, value=results)
        if value is not None:
            values[field.alias] = value
    for key, value in received_body.items():
        if key not in values:
            values[key] = value
    return values

				// The length of the expected ListObjectsResult.Objects
				// should match in both expected result from test cases
				// and in the output. On failure calling t.Fatalf,
				// otherwise it may lead to index out of range error in
				// assertion following this.
				if len(testCase.result.Objects) != len(result.Objects) {

 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,