type Person struct {
		ID       int
		Likes    []Thing `gorm:"many2many:likes"`
		Dislikes []Thing `gorm:"many2many:dislikes"`
	}

	checkStructRelation(t, &Person{},
		Relation{
			Name: "Likes", Type: schema.Many2Many, Schema: "Person", FieldSchema: "Thing",
			JoinTable: JoinTable{Name: "likes", Table: "likes"},
			References: []Reference{
				{"ID", "Person", "PersonID", "likes", "", true},

   *
   * <p>This method prioritizes convenience over performance: It reads the entire input into memory
   * immediately. To instead read and process lines individually, use an alternative like {@link
   * BufferedReader#lines()}.
   *
   * <p><b>Java 25+ users:</b> If the input is a {@link Reader}, you may prefer {@link
   * Reader#readAllLines()}. The two may have different performance characteristics for different

  @IgnoreJRERequirement
  public Stream<String> lines() throws IOException {
    BufferedReader reader = openBufferedStream();
    return reader.lines().onClose(() -> closeUnchecked(reader));
  }

  @IgnoreJRERequirement // helper for lines()
  /*
   * If we make these calls inline inside the lambda inside lines(), we get an Animal Sniffer error,

   *
   * {@snippet :
   * try (Stream<String> lines = source.lines()) {
   *   lines.map(...)
   *      .filter(...)
   *      .forEach(...);
   * }
   * }
   *
   * @throws IOException if an I/O error occurs while opening the stream
   * @since 22.0 (but only since 33.4.0 in the Android flavor)
   */
  @MustBeClosed
  public Stream<String> lines() throws IOException {

Remember how our app/file structure looks like:

<img src="/img/tutorial/bigger-applications/package.drawio.svg">

---

The two dots `..`, like in:

```Python
from ..dependencies import get_token_header
```

mean:

* Starting in the same package that this module (the file `app/routers/items.py`) lives in (the directory `app/routers/`)...

    * So, by using FastAPI you are saving development time, bugs, lines of code, and you would probably get the same performance (or better) you would if you didn't use it (as you would have to implement it all in your code).

{* ../../docs_src/path_operation_configuration/tutorial003_py310.py hl[18:19] *}

## Description from docstring { #description-from-docstring }

## Documenting the callback { #documenting-the-callback }

The actual callback code will depend heavily on your own API app.

And it will probably vary a lot from one app to the next.

It could be just one or two lines of code, like:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

$ export MY_NAME="Wade Wilson"

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

Hello Wade Wilson
```

</div>

////

//// tab | Windows PowerShell

<div class="termy">

```console
// Create an env var MY_NAME
$ $Env:MY_NAME = "Wade Wilson"

// Use it with other programs, like
$ echo "Hello $Env:MY_NAME"

Hello Wade Wilson
```

</div>

////

     * TLSv1.2
     * ```
     *
     * The file is newline separated. The first two lines are the URL and the request method. Next
     * is the number of HTTP Vary request header lines, followed by those lines.
     *
     * Next is the response status line, followed by the number of HTTP response header lines,
     * followed by those lines.
     *