private static final long serialVersionUID = 0;

  private final Function<? super F, ? extends @Nullable T> function;
  private final Equivalence<T> resultEquivalence;

  FunctionalEquivalence(
      Function<? super F, ? extends @Nullable T> function, Equivalence<T> resultEquivalence) {
    this.function = checkNotNull(function);
    this.resultEquivalence = checkNotNull(resultEquivalence);
  }

  @Override

e(e,d),b=42===f.offsetWidth,c.removeChild(e),{matches:b,media:a}}}(a.document)}(this),function(a){"use strict";function b(){u(!0)}var c={};a.respond=c,c.update=function(){};var d=[],e=function(){var b=!1;try{b=new a.XMLHttpRequest}catch(c){b=new a.ActiveXObject("Microsoft.XMLHTTP")}return function(){return b}}(),f=function(a,b){var c=e();c&&(c.open("GET",a,!0),c.onreadystatechange=function(){4!==c.readyState||200!==c.status&&304!==c.status||b(c.responseText)},4!==c.readyState&&c.send(null))};if(...

 *  @license MIT
 */

      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

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

import java.util.Arrays;
import java.util.Comparator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

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:"...

// name of the function handler passed (this handler must be a method of
// `adminAPIHandlers`).
//
// - sets up call to send AuditLog
//
// While this is a middleware function (i.e. it takes a handler function and
// returns one), due to flags being passed based on required conditions, it is
// done per-"handler function registration" in the router.
//

    * Cette extension SNI permet à un seul serveur (avec une seule adresse IP) d'avoir plusieurs certificats HTTPS et de servir plusieurs domaines/applications HTTPS.
    * Pour que cela fonctionne, un seul composant (programme) fonctionnant sur le serveur, écoutant sur l'adresse IP publique, doit avoir tous les certificats HTTPS du serveur.

      text: "SA1019: package github.com/golang/protobuf/jsonpb"
    - linters:
        - staticcheck
      text: 'SA1019: "github.com/golang/protobuf/jsonpb"'
    # This is not helpful. The new function is not very usable and the current function will not be removed
    - linters:
        - staticcheck
      text: 'SA1019: grpc.Dial is deprecated: use NewClient instead'
    - linters:
        - staticcheck