* In the key `content`, that has as value another JSON object (`dict`) that contains:
    * A key with the media type, e.g. `application/json`, that contains as value another JSON object, that contains:
        * A key `schema`, that has as the value the JSON Schema from the model, here's the correct place.

* There's a subdirectory `app/routers/` with another file `__init__.py`, so it's a "Python subpackage": `app.routers`.
* The file `app/routers/items.py` is inside a package, `app/routers/`, so, it's a submodule: `app.routers.items`.
* The same with `app/routers/users.py`, it's another submodule: `app.routers.users`.
* There's also a subdirectory `app/internal/` with another file `__init__.py`, so it's another "Python subpackage": `app.internal`.

      readyQueues.add(queue)

      // If the task crashed, start another thread to run the next task.
      if (!completedNormally) {
        startAnotherThread()
      }
    }
  }

  /**
   * Returns an immediately-executable task for the calling thread to execute, sleeping as necessary
   * until one is ready. If there are no ready queues, or if other threads have everything under

You can also declare a body as a `dict` with keys of some type and values of some other type.

This way, you don't have to know beforehand what the valid field/attribute names are (as would be the case with Pydantic models).

This would be useful if you want to receive keys that you don't already know.

---

Another useful case is when you want to have keys of another type (e.g., `int`).

That's what we are going to see here.

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

For example, if some code at some point in the middle, in another dependency or in a *path operation*, made a database transaction "rollback" or create any other error, you will receive the exception in your dependency.

So, you can look for that specific exception inside the dependency with `except SomeException`.

Then you can create another dependency function (a "dependable") that at the same time declares a dependency of its own (so it is a "dependant" too):

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[13] *}

Let's focus on the parameters declared:

* Even though this function is a dependency ("dependable") itself, it also declares another dependency (it "depends" on something else).

And be compatible with all of them at the same time.

///

Create a utility function to hash a password coming from the user.

And another utility to verify if a received password matches the hash stored.

And another one to authenticate and return a user.

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

<div class="termy">

```console
$ python myapp.py
```

</div>

but is not called when another file imports it, like in:

```Python
from myapp import app
```

#### More details { #more-details }

Let's say your file is named `myapp.py`.

If you run it with:

<div class="termy">

# Security - First Steps { #security-first-steps }

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

    /** All pipe instances are busy */
    int NT_STATUS_PIPE_BUSY = 0xC00000ae;
    /** No process is on the other end of the pipe */
    int NT_STATUS_PIPE_DISCONNECTED = 0xC00000b0;
    /** The pipe is being closed */
    int NT_STATUS_PIPE_CLOSING = 0xC00000b1;
    /** Waiting for a process to open the other end of the pipe */
    int NT_STATUS_PIPE_LISTENING = 0xC00000b3;
    /** The file that was specified is a directory */