responses returned by OkHttp itself, and it was an old mistake to permit
    application code to omit a message.

 *  The challenge's scheme and realm are now non-null. If you are calling
    `new Challenge(scheme, realm)` you must provide non-null values. These were
    never null in challenges created by OkHttp, but could have been null in
    application code that creates challenges.

/// tip

By default, `uv` will create a virtual environment in a directory called `.venv`.

But you could customize it passing an additional argument with the directory name.

///

////

That command creates a new virtual environment in a directory called `.venv`.

/// details | `.venv` or other name

You could create the virtual environment in a different directory, but there's a convention of calling it `.venv`.

   * our class loader (which could be that of a dynamically loaded web application or OSGi bundle),
   * it would prevent our class loader from getting garbage collected.
   */
  static class DecoupledLoader implements FinalizerLoader {
    private static final String LOADING_ERROR =
        "Could not load Finalizer in its own class loader. Loading Finalizer in the current class "

If you don't know, you will learn what a "password hash" is in the [security chapters](security/simple-oauth2.md#password-hashing).

///

## Multiple models { #multiple-models }

Here's a general idea of how the models could look like with their password fields and the places where they are used:

{* ../../docs_src/extra_models/tutorial001_py310.py hl[7,9,14,20,22,27:28,31:33,38:39] *}

### About `**user_in.model_dump()` { #about-user-in-model-dump }

    # Enable MMA Dynamic Dispatch support if 'gcc' and if linker >= 2.35
    gcc_env = get_gcc_compiler(environ_cp)
    if gcc_env is not None:

      # Use gold linker if 'gcc' and if 'ppc64le'
      write_to_bazelrc('build --linkopt="-fuse-ld=gold"')

      # Get the linker version
      ld_version = run_shell([gcc_env, '-Wl,-version']).split()

      ld_version_int = 0
      for i in range(len(ld_version)):

    public static final String MAVEN_STYLE_TRACE_DEFAULT = "bold,f:magenta";
    public static final String MAVEN_STYLE_DEBUG_DEFAULT = "bold,f:cyan";
    public static final String MAVEN_STYLE_INFO_DEFAULT = "bold,f:blue";
    public static final String MAVEN_STYLE_WARNING_DEFAULT = "bold,f:yellow";
    public static final String MAVEN_STYLE_ERROR_DEFAULT = "bold,f:red";

// ServeHTTP - implements http.Handler interface.
//
// When the `list` query parameter is provided (its value is ignored), the
// server lists all metrics that could be returned for the requested path.
//
// The (repeatable) `buckets` query parameter is a list of bucket names (or it
// could be a comma separated value) to return metrics with a bucket label.
// Bucket metrics will be returned only for the provided buckets. If no buckets

have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

Being able to use asynchronous functions in your tests could be useful, for example, when you're querying your database asynchronously. Imagine you want to test sending requests to your FastAPI application and then verify that your backend successfully wrote the correct data in the database, while using an async...

    expected.addAll(index, elements);
    expectContents(expected);
  }

  /*
   * TODO: if we're testing a list, we could check indexOf(). (Doing it in
   * AbstractListTester isn't enough because many tests that run on lists don't
   * extends AbstractListTester.) We could also iterate over all elements to
   * verify absence
   */
  protected void expectMissing(E... elements) {
    for (E element : elements) {

As seen in [Return a Response directly](response-directly.md), you can also override the response directly in your *path operation*, by returning it.

The same example from above, returning an `HTMLResponse`, could look like:

{* ../../docs_src/custom_response/tutorial003_py310.py hl[2,7,19] *}

/// warning