///

## Reduce duplication { #reduce-duplication }

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

As code duplication increments the chances of bugs, security issues, code desynchronization issues (when you update in one place but not in the others), etc.

Die unterstützenden zusätzlichen Funktionen `fake_password_hasher` und `fake_save_user` dienen nur zur Demo eines möglichen Datenflusses, bieten jedoch natürlich keine echte Sicherheit.

///

## Verdopplung vermeiden { #reduce-duplication }

Die Reduzierung von Code-Verdoppelung ist eine der Kernideen von **FastAPI**.

///

/// check

The `prefix`, `tags`, `responses`, and `dependencies` parameters are (as in many other cases) just a feature from **FastAPI** to help you avoid code duplication.

///

### Import the dependencies { #import-the-dependencies }

This code lives in the module `app.routers.items`, the file `app/routers/items.py`.

Las funciones adicionales de soporte `fake_password_hasher` y `fake_save_user` son solo para demostrar un posible flujo de datos, pero por supuesto no proporcionan ninguna seguridad real.

///

## Reducir duplicación { #reduce-duplication }

Reducir la duplicación de código es una de las ideas centrales en **FastAPI**.

* **Easy**: Designed to be easy to use and learn. Less time reading docs.
* **Short**: Minimize code duplication. Multiple features from each parameter declaration. Fewer bugs.
* **Robust**: Get production-ready code. With automatic interactive documentation.

* **Easy**: Designed to be easy to use and learn. Less time reading docs.
* **Short**: Minimize code duplication. Multiple features from each parameter declaration. Fewer bugs.
* **Robust**: Get production-ready code. With automatic interactive documentation.

One of the **biggest benefits** is that now you can create `Annotated` dependencies that are then shared by multiple *path operation functions*, this will allow you to **reduce** a lot of **code duplication** in your codebase, while keeping all the support from editors and tools.

For example, you could have code like this:

```Python
def get_current_user(token: str):
    # authenticate user