import okhttp3.Address
import okhttp3.HttpUrl

/**
 * Policy on choosing which connection to use for an exchange and any retries that follow. This uses
 * the following strategies:
 *
 *  1. If the current call already has a connection that can satisfy the request it is used. Using
 *     the same connection for an initial exchange and its follow-ups may improve locality.
 *

**FastAPI** is all based on these type hints, they give it many advantages and benefits.

But even if you never use **FastAPI**, you would benefit from learning a bit about them.

/// note

If you are a Python expert, and you already know everything about type hints, skip to the next chapter.

///

## Motivation { #motivation }

Let's start with a simple example:

{* ../../docs_src/python_types/tutorial001.py *}

public interface RemovalListener<K, V> {
  /**
   * Notifies the listener that a removal occurred at some point in the past.
   *
   * <p>This does not always signify that the key is now absent from the cache, as it may have
   * already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because
  // RemovalNotification is guaranteed covariant, let's make users' lives simpler.

  }

  // TODO(cpovirk): Use standard Javadoc form for SimpleForwarding* class and constructor
  /**
   * A simplified version of {@link ForwardingListenableFuture} where subclasses can pass in an
   * already constructed {@link ListenableFuture} as the delegate.
   *
   * @since 9.0
   */
  public abstract static class SimpleForwardingListenableFuture<V extends @Nullable Object>
      extends ForwardingListenableFuture<V> {

  fun request(): Request

  /**
   * Immediately and violently release resources held by this event source. This does nothing if
   * the event source has already been closed or canceled.
   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new event source and immediately returns it. Creating an event source initiates an

import com.google.common.annotations.J2ktIncompatible;
import org.jspecify.annotations.Nullable;

/**
 * An {@link ImmutableAsList} implementation specialized for when the delegate collection is already
 * backed by an {@code ImmutableList} or array.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace, not default serialization

 * Maven stores all the downloaded artifacts (such as dependencies, plugins,
 * and project artifacts). When Maven builds a project, it first checks the
 * local repository to see if the required artifacts are already available.
 * If the artifacts are found locally, Maven uses them directly, which speeds
 * up the build process by avoiding unnecessary downloads.</p>
 *

    /**
     * This returns true if the file's attributes contain any of the attributes
     * specified for this filter. The wildcard has no influence on this
     * method as the server should have performed that filtering already. The
     * attributes are asserted here only because server file systems may not
     * support filtering by all attributes (e.g. even though ATTR_DIRECTORY was

Using Linux containers has several advantages including **security**, **replicability**, **simplicity**, and others.

/// tip

In a hurry and already know this stuff? Jump to the [`Dockerfile` below 👇](#build-a-docker-image-for-fastapi).

///

<details>
<summary>Dockerfile Preview 👀</summary>

```Dockerfile
FROM python:3.9

WORKDIR /code

        assertEquals(0, message.getFlags(), "Flag 0b0100 should be cleared.");

        // Test setting a flag that is already set
        message.setFlags(0b1000);
        message.setFlag(0b1000, true);
        assertEquals(0b1000, message.getFlags(), "Setting an already set flag should not change other flags.");

        // Test clearing a flag that is not set
        message.setFlags(0b1000);