As code duplication increments the chances of bugs, security issues, code desynchronization issues (when you update in one place but not in the others), etc.

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

		{"117Gn8rfHL2ACARPAhaFd0AGzic9pUbIA/5OCn5A", []int{3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 1, 2}},
		{"SHØRT", []int{11, 12, 13, 14, 15, 16, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}},
		{"There are far too many object names, and far too few bucket names!", []int{15, 16, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}},
		{"a/b/c/", []int{3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 1, 2}},
		{"/a/b/c", []int{6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 1, 2, 3, 4, 5}},

 * The query is optional: it can be null, empty, or non-empty. For many HTTP URLs the query string
 * is subdivided into a collection of name-value parameters. This class offers methods to set the
 * query as the single string, or as individual name-value parameters. With name-value parameters
 * the values are optional and names may be repeated.
 *
 * ### Fragment
 *

    int CONN_TIMEOUT = Config.getInt("jcifs.smb1.smb.client.connTimeout", DEFAULT_CONN_TIMEOUT);
    /** Native operating system name */
    String NATIVE_OS = Config.getProperty("jcifs.smb1.smb.client.nativeOs", System.getProperty("os.name"));
    /** Native LAN manager name */
    String NATIVE_LANMAN = Config.getProperty("jcifs.smb1.smb.client.nativeLanMan", "jCIFS");
    /** Virtual circuit number */
    int VC_NUMBER = 1;

	// Add some files to the archive.
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling licence.\nWrite more examples."},
	}
	for _, file := range files {
		f, err := w.Create(file.Name)
		if err != nil {
			log.Fatal(err)
		}
		_, err = f.Write([]byte(file.Body))

     *
     * @return an {@link Optional} containing the project name to resume from, or empty if not specified
     */
    @Nonnull
    Optional<String> resumeFrom();

    /**
     * Returns the list of specified reactor projects to build instead of all projects.
     *
     * @return an {@link Optional} containing the list of project names to build, or empty if not specified
     */
    @Nonnull

This would mean that **FastAPI** would expect a body similar to:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

Again, doing just that declaration, with **FastAPI** you get:

  dependencies { osgiApi(kotlinOsgi) }

  tasks.named<GradleJar>("jvmJar").configure {
    val bundleExtension =
      extensions.create(
        BundleTaskExtension.NAME,
        BundleTaskExtension::class.java,
        this,
      )
    val osgiApiArtifacts = osgiApi.artifacts
    val jvmMainClasses = tasks.named("jvmMainClasses").map { it.outputs.files }
    bundleExtension.apply {

        bool,
        Doc(
            """
            Pydantic's `by_alias` parameter, passed to Pydantic models to define if
            the output should use the alias names (when provided) or the Python
            attribute names. In an API, if you set an alias, it's probably because you
            want to use it in the result, so you probably want to leave this set to
            `True`.
            """
        ),

	// Test that we can get the files back from the archive
	tr := NewReader(&buf)

	names := make([]string, 0, len(fsys))
	for name := range fsys {
		names = append(names, name)
	}
	sort.Strings(names)

	entriesLeft := len(fsys)
	for _, name := range names {
		entriesLeft--

		entryInfo, err := fsys.Lstat(name)
		if err != nil {
			t.Fatalf("getting entry info error: %v", err)
		}