// didn't see it, trying to put it instead...
        Dummy sneaky = map.putIfAbsent(sample, Dummy.VALUE);
        if (sneaky == null) {
          return sample;
        } else {
          /* Someone beat us to it! Trying again...
           *
           * Technically this loop not guaranteed to terminate, so theoretically (extremely
           * unlikely) this thread might starve, but even then, there is always going to be another

///

Dann könnten Sie dieses Python-Programm aufrufen:

<div class="termy">

```console
// Hier legen wir die Umgebungsvariable noch nicht fest
$ python main.py

// Da wir die Umgebungsvariable nicht festgelegt haben, erhalten wir den Standardwert

Hello World from Python

// Aber wenn wir zuerst eine Umgebungsvariable erstellen

### Documentation

- Feat: azure file migration go beta in 1.21. Feature gates CSIMigration to Beta (on by default) and CSIMigrationAzureFile to Beta (off by default since it requires installation of the AzureFile CSI Driver)

      <fields>
        <field>
          <name>toolchains</name>
          <version>1.0.0+</version>
          <description>The toolchain instance definition.</description>
          <association xml.itemsStyle="flat">
            <type>ToolchainModel</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>
      </fields>
    </class>
    <class>
      <name>ToolchainModel</name>

xpand):hover .nav-compact.nav-sidebar.nav-child-indent:not(.nav-flat) .nav-treeview{padding-left:1rem;margin-left:-.5rem}.nav-flat{margin:-.25rem -.5rem 0}.nav-flat .nav-item>.nav-link{border-radius:0;margin-bottom:0}.nav-flat .nav-item>.nav-link>.nav-icon{margin-left:.55rem}.nav-flat:not(.nav-child-indent) .nav-treeview .nav-item>.nav-link>.nav-icon{margin-left:.4rem}.nav-flat.nav-child-indent .nav-treeview{padding-left:0}.nav-flat.nav-child-indent .nav-treeview .nav-icon{margin-left:.85rem}.na...

```

////

//// tab | Python 3.8+

```Python hl_lines="14"
{!> ../../docs_src/body_nested_models/tutorial002.py!}
```

////

## Set-Typen

Aber dann denken wir darüber nach und stellen fest, dass sich die Tags nicht wiederholen sollen, es sollen eindeutige Strings sein.

Python hat einen Datentyp speziell für Mengen eindeutiger Dinge: das <abbr title="Menge">`set`</abbr>.

  integrity sha512-PpOwAdQ/YlXQ2vj8a3h8IipDuYRi3wceVQQGYWxNINccq40Anw7BlsEXCMbt1Zt+OLA6Fq9suIpIWD0OsnISlw==
  dependencies:
    locate-path "^5.0.0"
    path-exists "^4.0.0"

flat@^5.0.2:
  version "5.0.2"
  resolved "https://registry.yarnpkg.com/flat/-/flat-5.0.2.tgz#8ca6fe332069ffa9d324c327198c598259ceb241"
  integrity sha512-b6suED+5/3rTpUBdG1gupIl8MPFCAMA0QXwmljLhvCUKcUvdE4gWky9zpuGCcXHOsz4J9wPGNWq6OKpmIzz3hQ==

flatted@^3.2.7:

something()
```

oder

```Python
something(some_argument, some_keyword_argument="foo")
```

dann ist das ein „Callable“ (ein „Aufrufbares“).

## Klassen als Abhängigkeiten

Möglicherweise stellen Sie fest, dass Sie zum Erstellen einer Instanz einer Python-Klasse die gleiche Syntax verwenden.

Zum Beispiel:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name

.nav-treeview .nav-icon {\n  margin-left: 2.05rem;\n}\n\n.nav-flat .nav-icon {\n  transition: margin-left ease-in-out 0.3s;\n}\n\n@media (prefers-reduced-motion: reduce) {\n  .nav-flat .nav-icon {\n    transition: none;\n  }\n}\n\n.nav-flat .nav-treeview .nav-icon {\n  margin-left: -.2rem;\n}\n\n.nav-flat.nav-sidebar > .nav-item .nav-treeview,\n.nav-flat.nav-sidebar > .nav-item > .nav-treeview {\n  background-color: rgba(255, 255, 255, 0.05);\n}\n\n.nav-flat.nav-sidebar > .nav-item .nav-treeview .nav-item >...

 *       code, or even to discover <i>any</i> two distinct inputs that yield the same result. These
 *       are called <i>cryptographic hash functions</i>. But, whenever it is learned that either of
 *       these feats has become computationally feasible, the function is deemed "broken" and should
 *       no longer be used for secure purposes. (This is the likely eventual fate of <i>all</i>
 *       cryptographic hashes.)