* **`400 - 499`** are for "Client error" responses. These are the second type you would probably use the most.
    * An example is `404`, for a "Not Found" response.
    * For generic errors from the client, you can just use `400`.
* `500 - 599` are for server errors. You almost never use them directly. When something goes wrong at some part in your application code, or server, it will automatically return one of these status codes.

## Create and Use Env Vars { #create-and-use-env-vars }

You can **create** and use environment variables in the **shell (terminal)**, without needing Python:

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console
// You could create an env var MY_NAME with
$ export MY_NAME="Wade Wilson"

// Then you could use it with other programs, like
$ echo "Hello $MY_NAME"

    val iterator = cache.snapshots()
    assertThat(iterator.hasNext()).isTrue()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("a")
      it.assertValue(0, "a1")
      it.assertValue(1, "a2")
    }
    assertThat(iterator.hasNext()).isTrue()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("b")
      it.assertValue(0, "b1")
      it.assertValue(1, "b2")
    }

If you have an older version, you would get errors when trying to use `Annotated`.

Make sure you [Upgrade the FastAPI version](../deployment/versions.md#upgrading-the-fastapi-versions){.internal-link target=_blank} to at least 0.95.1 before using `Annotated`.

///

## Use `Annotated` in the type for the `q` parameter { #use-annotated-in-the-type-for-the-q-parameter }

        str,
        Doc(
            """
            The URL to use to load the Swagger UI JavaScript.

            It is normally set to a CDN URL.
            """
        ),
    ] = "https://cdn.jsdelivr.net/npm/swagger-ui-dist@5/swagger-ui-bundle.js",
    swagger_css_url: Annotated[
        str,
        Doc(
            """
            The URL to use to load the Swagger UI CSS.

            It is normally set to a CDN URL.

/*
 * Copyright (C) 2013 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2015 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

     */
    protected static final String UNI_ENCODING = "UTF-16LE";

    private int flags;

    /**
     * Returns the flags currently in use for this message.
     *
     * @return An <code>int</code> containing the flags in use for this
     *         message.
     */
    public int getFlags() {
        return this.flags;
    }

    /**
     * Sets the flags for this message.
     *

import org.mockito.junit.jupiter.MockitoExtension;

import jcifs.smb1.UniAddress;

/**
 * Very small test suite that exercises the most important state-changing
 * behaviour of {@link SmbSession}. The tests use Mockito to stub the
 * heavy network interactions through {@link SmbTransport}.
 */
@ExtendWith(MockitoExtension.class)
public class SmbSessionTest {

    @Mock
    UniAddress addr;
    @Mock

 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,