/**
     * Creates a composite function from a collection of functions.
     *
     * @param functions A collection of functions, each taking a String as input and returning a String.
     * @return A function that applies each function in the collection in order until a non-null result is found.
     *         If all functions return null, the composite function returns null.
     *

### Otras funciones de utilidad { #other-utility-functions }

Cualquier otra función de utilidad que llames directamente puede ser creada con `def` normal o `async def` y FastAPI no afectará la forma en que la llames.

Esto contrasta con las funciones que FastAPI llama por ti: *path operation functions* y dependencias.

Let's first focus on the dependency.

It is just a function that can take all the same parameters that a *path operation function* can take:

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[8:9] *}

That's it.

**2 lines**.

And it has the same shape and structure that all your *path operation functions* have.

You can think of it as a *path operation function* without the "decorator" (without the `@app.get("/some-path")`).

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")
        function ->> execute: führe Code der Funktion aus
        execute ->> code: gib das Resultat zurück
    end

    rect rgba(0, 255, 255, .1)
        code ->> function: say_hi(name="Camila")
        function ->> code: gib das gespeicherte Resultat zurück
    end

    rect rgba(0, 255, 0, .1)

  // Add a function (serialized FunctionDef protocol buffer) so that it can
  // be executed as an op. Return error if the function with the same name
  // already exists.
  virtual absl::Status AddFunctionDef(const FunctionDef& fdef) = 0;

  // Notifies about the function removal.
  virtual absl::Status AddRemoveFunctionNotifier(
      const string& func, std::function<void()> notifier) = 0;

### Inclure les docs personnalisées { #include-the-custom-docs }

Vous pouvez maintenant créer les chemins d'accès pour les docs personnalisées.

Vous pouvez réutiliser les fonctions internes de FastAPI pour créer les pages HTML de la documentation et leur passer les arguments nécessaires :

    <function-class>org.codelibs.fess.taglib.FessFunctions</function-class>
    <function-signature>java.lang.String mltForm()</function-signature>
    <example>
      ${fe:mltForm()}
    </example>
  </function>

  <function>
    <description>
      Returns a hidden form for Geo.
    </description>
    <name>geoForm</name>
    <function-class>org.codelibs.fess.taglib.FessFunctions</function-class>

import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.collect.testing.MapInterfaceTest;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

Maybe you need to start a new version, or you just got tired of running it. 🤷

///

### Lifespan function { #lifespan-function }

The first thing to notice, is that we are defining an async function with `yield`. This is very similar to Dependencies with `yield`.

{* ../../docs_src/events/tutorial003_py310.py hl[14:19] *}

The first part of the function, before the `yield`, will be executed **before** the application starts.

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import java.util.HashMap;
import java.util.Map;
import org.jspecify.annotations.NullMarked;

/**
 * Tests for {@link Maps#transformValues(Map, Function)}.
 *
 * @author Isaac Shum
 */
@GwtCompatible
@NullMarked