# Environment Variables

/// tip

If you already know what "environment variables" are and how to use them, feel free to skip this.

///

An environment variable (also known as "**env var**") is a variable that lives **outside** of the Python code, in the **operating system**, and could be read by your Python code (or by other programs as well).

    }
    val requestBody = (call.request().body as AsyncRequestBody?)!!.takeSink()
    assertFailsWith<IOException> {
      requestBody.writeUtf8("request body\n")
      requestBody.flush()
    }.also { expected ->
      assertThat(expected.message)
        .isEqualTo("stream was reset: CANCEL")
    }
    body.awaitSuccess()
    assertThat(listener.recordedEventTypes()).containsExactly(

**FastAPI** will use that *temporal* response to extract the status code (also cookies and headers), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

  /**
   * Add {@code node} as a predecessor to the origin node. In the case of an undirected graph, it
   * also becomes a successor. Associates {@code value} with the edge connecting the two nodes.
   */
  void addPredecessor(N node, V value);

  /**
   * Add {@code node} as a successor to the origin node. In the case of an undirected graph, it also
   * becomes a predecessor. Associates {@code value} with the edge connecting the two nodes. Returns

Dennoch sind die Fähigkeiten von Uvicorn zur Abwicklung von Workerprozessen derzeit eingeschränkter als die von Gunicorn. Wenn Sie also einen Prozessmanager auf dieser Ebene (auf der Python-Ebene) haben möchten, ist es vermutlich besser, es mit Gunicorn als Prozessmanager zu versuchen.

Wie auch immer, Sie würden es so ausführen:

<div class="termy">

```console

        .build()
    val request =
      Request.Builder()
        .url(server.url("/"))
        .build()
    assertFailsWith<IllegalStateException> {
      client.newCall(request).execute()
    }.also { expected ->
      assertThat(expected.message).isEqualTo(
        "network interceptor $interceptor must call proceed() exactly once",
      )
    }
  }

  @Test

 * server's hostname and port. If an explicit proxy is requested (or [no proxy][Proxy.NO_PROXY] is
 * explicitly requested), this also includes that proxy information. For secure connections the
 * address also includes the SSL socket factory, hostname verifier, and certificate pinner.
 *
 * HTTP requests that share the same [Address] may also share the same [Connection].
 */
class Address(
  uriHost: String,
  uriPort: Int,

Um Header zu deklarieren, müssen Sie `Header` verwenden, da diese Parameter sonst als Query-Parameter interpretiert werden würden.

///

## Automatische Konvertierung

`Header` hat weitere Funktionalität, zusätzlich zu der, die `Path`, `Query` und `Cookie` bereitstellen.

Die meisten Standard-Header benutzen als Trennzeichen einen Bindestrich, auch bekannt als das „Minus-Symbol“ (`-`).

`0.5` wäre also ein gültiger Wert, aber nicht `0.0` oder `0`.

Das gleiche gilt für <abbr title="less than – kleiner als"><code>lt</code></abbr>.

The spec also states that the `username` and `password` must be sent as form data (so, no JSON here).

### `scope`

The spec also says that the client can send another form field "`scope`".