/**
 * Legacy version of {@link java.util.function.Function java.util.function.Function}.
 *
 * <p>The {@link Functions} class provides common functions and related utilities.
 *
 * <p>As this interface extends {@code java.util.function.Function}, an instance of this type can be
 * used as a {@code java.util.function.Function} directly. To use a {@code
 * java.util.function.Function} in a context where a {@code com.google.common.base.Function} is

   * typically by writing {@code (Function<Object, String> & Serializable) Object::toString}.
   *
   * <p>For more important information about the transition from Guava's {@link Function} class to
   * the JDK {@link java.util.function.Function} class, see {@link Function}.
   */
  public static Function<Object, String> toStringFunction() {
    return ToStringFunction.INSTANCE;
  }

    Function<? super Integer, Boolean> h = Functions.constant(Boolean.TRUE);
    Function<? super String, Integer> g = new HashCodeFunction();
    Function<Float, String> f = Functions.forMap(m, "F");

    Function<Float, Boolean> c1 = Functions.compose(Functions.compose(h, g), f);
    Function<Float, Boolean> c2 = Functions.compose(h, Functions.compose(g, f));

{* ../../docs_src/background_tasks/tutorial001.py hl[1,13] *}

**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function { #create-a-task-function }

Create a function to be run as the background task.

It is just a standard function that can receive parameters.

  }

  /**
   * 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
   */
  @FunctionalInterface
  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.
     *

      searchForm: $("#searchForm")
    });
  }

  loadImage = function(img, url, limit) {
    var imgData = new Image();
    $(imgData).on("load", function() {
      $(img).css("background-image", "");
      $(img).attr("src", url);
    });
    $(imgData).on("error", function() {
      if (limit > 0) {
        setTimeout(function() {
          loadImage(img, url, --limit);
        }, IMG_LOADING_DELAY);

      for (HashFunction function : functions) {
        bitSum += function.bits();
      }
      return bitSum;
    }

    @Override
    public boolean equals(@Nullable Object object) {
      if (object instanceof ConcatenatedHashFunction) {
        ConcatenatedHashFunction other = (ConcatenatedHashFunction) object;
        return Arrays.equals(functions, other.functions);
      }
      return false;

///

## Other Asynchronous Function Calls { #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

   *
   * @param function A Function to transform the results of this future to the results of the
   *     returned future.
   * @param executor Executor to run the function in.
   * @return A future that holds result of the transformation.
   */
  public final <T extends @Nullable Object> FluentFuture<T> transform(
      Function<? super V, T> function, Executor executor) {

      implements Serializable {
    private final Function<? super A, ? extends B> forwardFunction;
    private final Function<? super B, ? extends A> backwardFunction;

    private FunctionBasedConverter(
        Function<? super A, ? extends B> forwardFunction,
        Function<? super B, ? extends A> backwardFunction) {
      this.forwardFunction = checkNotNull(forwardFunction);