import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import com.google.common.testing.NullPointerTester;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.function.Function;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * A {@link RangeMap} whose contents will never change, with many other important properties

import static com.google.common.cache.LocalCache.Strength.STRONG;
import static com.google.common.collect.Maps.immutableEntry;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.base.Function;
import com.google.common.cache.LocalCache.Strength;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import java.lang.ref.WeakReference;
import junit.framework.TestCase;

Es kann sich um eine `async def`- oder normale `def`-Funktion handeln. **FastAPI** weiß, wie damit zu verfahren ist.

In diesem Fall schreibt die Taskfunktion in eine Datei (den Versand einer E-Mail simulierend).

Und da der Schreibvorgang nicht `async` und `await` verwendet, definieren wir die Funktion mit normalem `def`:

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

import static org.codelibs.core.stream.StreamUtil.stream;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.BiPredicate;
import java.util.function.Predicate;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.misc.Tuple3;

   *
   * @return the composition of the provided function and predicate
   */
  public static <A extends @Nullable Object, B extends @Nullable Object> Predicate<A> compose(
      Predicate<B> predicate, Function<A, ? extends B> function) {
    return new CompositionPredicate<>(predicate, function);
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the {@code CharSequence} being tested

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.base.Function;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.ForwardingWrapperTester;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**

type currentPathTracker struct {
	name *unsafe.Pointer // contains atomically accessed *string
}

// currentPathUpdater provides a lightweight update function for keeping track of
// current objects for each disk.
// Returns a function that can be used to update the current object
// and a function to call to when processing finished.
func (p *scannerMetrics) currentPathUpdater(disk, initial string) (update func(path string), done func()) {

	// baseDir is not honored in windows platform
	return os.MkdirAll(dirPath, perm)
}

// readDirFn applies the fn() function on each entries at dirPath, doesn't recurse into
// the directory itself, if the dirPath doesn't exist this function doesn't return
// an error.
func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error) error {
	// Ensure we don't pick up files as directories.

			cleanupFns[i]()
		}
		return nil, PreConditionFailed{}
	}
	return &GetObjectReader{
		ObjInfo:    oi,
		Reader:     r,
		cleanUpFns: cleanupFns,
	}, nil
}

// ObjReaderFn is a function type that takes a reader and returns
// GetObjectReader and an error. Request headers are passed to provide
// encryption parameters. cleanupFns allow cleanup funcs to be
// registered for calling after usage of the reader.