Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example { #a-dict-from-the-previous-example }

In the previous example, we were returning a `dict` from our dependency ("dependable"):

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

But then we get a `dict` in the parameter `commons` of the *path operation function*.

NAMESPACE com.google.common.escape
NAMESPACE com.google.common.escape.testing
NAMESPACE com.google.common.io
NAMESPACE com.google.common.net
NAMESPACE com.google.common.testing

# Allow our dependencies for now.
NAMESPACE junit.framework
NAMESPACE org.junit

# ***** REAL CYCLES *****
# Cycle exists until future completes

import org.jspecify.annotations.NullMarked;

/**
 * Disables Animal Sniffer's checking of compatibility with older versions of Java/Android.
 *
 * <p>Each package's copy of this annotation needs to be listed in our {@code pom.xml}.
 */
@Target({METHOD, CONSTRUCTOR, TYPE, FIELD})
@NullMarked

But doing that, in some minutes or hours the attackers would have guessed the correct username and password, with the "help" of our application, just using the time taken to answer.

#### Fix it with `secrets.compare_digest()` { #fix-it-with-secrets-compare-digest }

But in our code we are actually using `secrets.compare_digest()`.

   * to calling it exactly once.
   *
   * @since 10.0 (present in 1.0 as {@code run})
   */
  public void execute() {
    // Lock while we update our state so the add method above will finish adding any listeners
    // before we start to run them.
    RunnableExecutorPair list;
    synchronized (lock) {
      if (executed) {
        return;
      }

 */

package org.elasticsearch.gradle.internal.docker;

import java.util.stream.Collectors;
import java.util.stream.IntStream;

/**
 * The methods in this class take a shell command and wrap it in retry logic, so that our
 * Docker builds can be more robust in the face of transient errors e.g. network issues.
 */
public class ShellRetry {
    static String loop(String name, String command) {
        return loop(name, command, 4, "exit");

In this case, **FastAPI** won't ever touch or care about `__init__`, we will use it directly in our code.

## Create an instance { #create-an-instance }

We could create an instance of this class with:

{* ../../docs_src/dependencies/tutorial011_an_py310.py hl[18] *}

And that way we are able to "parameterize" our dependency, that now has `"bar"` inside of it, as the attribute `checker.fixed_content`.

 *
 * We use this because eager classpath checks cause confusion and excessive logging in Android,
 * and we can't rely on classnames after proguard, so are probably best served by falling through
 * to a situation of trying our least likely noisiest options.
 */
class DeferredSocketAdapter(
  private val socketAdapterFactory: Factory,
) : SocketAdapter {
  private var delegate: SocketAdapter? = null

        };

    assertFalse(fakePool.hasNext());
    e.execute(intCounter);
    // A task should have been scheduled
    assertTrue(fakePool.hasNext());
    e.execute(intCounter);
    // Our executor hasn't run any tasks yet.
    assertEquals(0, totalCalls.get());
    fakePool.runAll();
    assertEquals(2, totalCalls.get());
    // Queue is empty so no runner should be scheduled.

 * ListenableFuture} directly.
 *
 * @author Sven Mawson
 * @author Nishant Thakkar
 * @since 1.0
 */
/*
 * Some of the annotations below were added after we released our separate
 * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
 * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture