You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

It declares an optional query parameter `q` as a `str`, and then it just returns it.

This is quite simple (not very useful), but will help us focus on how the sub-dependencies work.

## Second dependency, "dependable" and "dependant" { #second-dependency-dependable-and-dependant }

You could also use `from starlette import status`.

**FastAPI** provides the same `starlette.status` as `fastapi.status` just as a convenience for you, the developer. But it comes directly from Starlette.

///

## Tags { #tags }

You can add tags to your *path operation*, pass the parameter `tags` with a `list` of `str` (commonly just one `str`):

{* ../../docs_src/path_operation_configuration/tutorial002_py310.py hl[15,20,25] *}

   *
   * <p>This method is useful primarily when we make a reflective call to a method with no {@code
   * throws} clause: Java forces us to handle an arbitrary {@link Throwable} from that method,
   * rather than just the {@link RuntimeException} or {@link Error} that should be possible. (And in
   * fact the static type of {@link Throwable} is occasionally justified even for a method with no

That doesn't add any extra security to your API, the *path operations* will still be available where they are.

If there's a security flaw in your code, it will still exist.

```Python hl_lines="2"
@app.get('/')
def results():
    results = some_library()
    return results
```

---

If your application (somehow) doesn't have to communicate with anything else and wait for it to respond, use `async def`, even if you don't need to use `await` inside.

---

If you just don't know, use normal `def`.

---

 * is computed from the monotonic duration since system start to ensure consistency
 * between time measurements.
 * <p>
 * This implementation is singleton-based and always uses UTC timezone. The clock
 * cannot be adjusted to different timezones to maintain consistent monotonic behavior.
 * Users needing local time representation should convert the result of {@link #instant()}
 * to their desired timezone:
 * <pre>{@code

          // In the case of a concurrent remove, we might observe a zero value, which means another
          // thread is about to remove (element, existingCounter) from the map. Rather than wait,
          // we can just do that work here.
          AtomicInteger newCounter = new AtomicInteger(occurrences);
          if ((countMap.putIfAbsent(element, newCounter) == null)
              || countMap.replace(element, existingCounter, newCounter)) {

from typing import Annotated


def say_hello(name: Annotated[str, "this is just metadata"]) -> str:

    full_name = user_dict["full_name"],
    hashed_password = hashed_password,
)
```

/// warning

The supporting additional functions `fake_password_hasher` and `fake_save_user` are just to demo a possible flow of the data, but they of course are not providing any real security.

///

## Reduce duplication { #reduce-duplication }

Reducing code duplication is one of the core ideas in **FastAPI**.

            copySpec.rename(s -> destinationFile.getName());

            // TODO: Maybe this could be simplified by not using the copy infrastructure and just
            // calling the FilterReader ourselves.  We're just taking one file and turning it into another.

            // The order here is important! tokens are inserted by the transformer
            Map<String, Object> parameters = new HashMap<>();