!!! tip
    You'll see what other "things", apart from functions, can be used as dependencies in the next chapter.

Whenever a new request arrives, **FastAPI** will take care of:

* Calling your dependency ("dependable") function with the correct parameters.
* Get the result from your function.
* Assign that result to the parameter in your *path operation function*.

```mermaid
graph TB

      Function<? super F, T> function, Supplier<F> supplier) {
    return new SupplierComposition<>(function, supplier);
  }

  private static class SupplierComposition<F extends @Nullable Object, T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    final Function<? super F, T> function;
    final Supplier<F> supplier;

    SupplierComposition(Function<? super F, T> function, Supplier<F> supplier) {

        execute ->> code: return the result
    end

    rect rgba(0, 255, 255, .1)
        code ->> function: say_hi(name="Camila")
        function ->> code: return stored result
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick")
        function ->> execute: execute function code
        execute ->> code: return the result
    end

   * {@code function} to the argument, then evaluating using {@code this}. That is, for any pair of
   * non-null objects {@code x} and {@code y}, {@code equivalence.onResultOf(function).equivalent(a,
   * b)} is true if and only if {@code equivalence.equivalent(function.apply(a), function.apply(b))}
   * is true.
   *
   * <p>For example:
   *
   * <pre>{@code

   * {@code function} to the argument, then evaluating using {@code this}. That is, for any pair of
   * non-null objects {@code x} and {@code y}, {@code equivalence.onResultOf(function).equivalent(a,
   * b)} is true if and only if {@code equivalence.equivalent(function.apply(a), function.apply(b))}
   * is true.
   *
   * <p>For example:
   *
   * <pre>{@code

when the function is invoked, not when the "defer" statement is executed.
</p>

<p>
For instance, if the deferred function is
a <a href="#Function_literals">function literal</a> and the surrounding
function has <a href="#Function_types">named result parameters</a> that
are in scope within the literal, the deferred function may access and modify
the result parameters before they are returned.

      Function<? super F, T> function, Supplier<F> supplier) {
    return new SupplierComposition<>(function, supplier);
  }

  private static class SupplierComposition<F extends @Nullable Object, T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    final Function<? super F, T> function;
    final Supplier<F> supplier;

    SupplierComposition(Function<? super F, T> function, Supplier<F> supplier) {

          V extends @Nullable Object,
          M extends Multimap<K, V>>
      Collector<T, ?, M> toMultimap(
          java.util.function.Function<? super T, ? extends K> keyFunction,
          java.util.function.Function<? super T, ? extends V> valueFunction,
          java.util.function.Supplier<M> multimapSupplier) {
    return CollectCollectors.<T, K, V, M>toMultimap(keyFunction, valueFunction, multimapSupplier);
  }

  /**

        functionCall: FirFunctionCall,
        mode: KtConstantEvaluationMode,
    ): FirLiteralExpression<*>? {
        val function = functionCall.getOriginalFunction() as? FirSimpleFunction ?: return null

        val opr1 = evaluate(functionCall.explicitReceiver, mode) ?: return null
        opr1.evaluate(function)?.let {
            return it.adjustType(functionCall.resolvedType)
        }

    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)