*         If all functions return null, the composite function returns null.
     *
     * @throws NullPointerException if the input collection is null or contains null elements.
     */
    static Function<String, String> chain(Collection<? extends Function<String, String>> functions) {
        return s -> {
            for (Function<String, String> function : functions) {
                String v = function.apply(s);

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Add the background task

emoveAttribute("id")}}}return re(t.replace(ve,"$1"),e,n,r)}function W(){var r=[];return function e(t,n){return r.push(t+" ")>b.cacheLength&&delete e[r.shift()],e[t+" "]=n}}function F(e){return e[S]=!0,e}function $(e){var t=T.createElement("fieldset");try{return!!e(t)}catch(e){return!1}finally{t.parentNode&&t.parentNode.removeChild(t),t=null}}function B(t){return function(e){return fe(e,"input")&&e.type===t}}function _(t){return function(e){return(fe(e,"input")||fe(e,"button"))&&e.type===t}}function...

      extends AbstractTransformFuture<I, O, Function<? super I, ? extends O>, O> {
    TransformFuture(
        ListenableFuture<? extends I> inputFuture, Function<? super I, ? extends O> function) {
      super(inputFuture, function);
    }

    @Override
    @ParametricNullness
    O doTransform(Function<? super I, ? extends O> function, @ParametricNullness I input) {
      return function.apply(input);
    }

    @Override

n=d.getTransitionDurationFromElement(t);o.default(t).one(d.TRANSITION_END,(function(n){return e._destroyElement(t,n)})).emulateTransitionEnd(n)}else this._destroyElement(t)},e._destroyElement=function(t){o.default(t).detach().trigger("closed.bs.alert").remove()},t._jQueryInterface=function(e){return this.each((function(){var n=o.default(this),i=n.data(c);i||(i=new t(this),n.data(c,i)),"close"===e&&i[e](this)}))},t._handleDismiss=function(t){return function(e){e&&e.preventDefault(),t.close(this)}},l(t,null,[{key:"...

          V,
          I extends Table<R, C, V>>
      Collector<T, ?, I> toTable(
          java.util.function.Function<? super T, ? extends R> rowFunction,
          java.util.function.Function<? super T, ? extends C> columnFunction,
          java.util.function.Function<? super T, ? extends V> valueFunction,
          java.util.function.Supplier<I> tableSupplier) {
    return TableCollectors.<T, R, C, V, I>toTable(

///

## Other Asynchronous Function Calls

As the testing function is now asynchronous, you can now also call (and `await`) other `async` functions apart from sending requests to your FastAPI application in your tests, exactly as you would call them anywhere else in your code.

/// tip

lter(t)[0]}function N(e,t,o){if(Array.prototype.findIndex)return e.findIndex(function(e){return e[t]===o});var n=D(e,function(e){return e[t]===o});return e.indexOf(n)}function P(t,o,n){var i=void 0===n?t:t.slice(0,N(t,'name',n));return i.forEach(function(t){t['function']&&console.warn('`modifier.function` is deprecated, use `modifier.fn`!');var n=t['function']||t.fn;t.enabled&&e(n)&&(o.offsets.popper=g(o.offsets.popper),o.offsets.reference=g(o.offsets.reference),o=n(o,t))}),o}function k(){if(!th...

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")`).

  }

  /**
   * A function from an input to a result.
   *
   * @param <T> the type of the input to the function
   * @param <U> the type of the result of the function
   */
  public interface ClosingFunction<T extends @Nullable Object, U extends @Nullable Object> {

    /**
     * Applies this function to an input, or throws an exception if unable to do so.
     *