}
}

/**
 * Reads lines from `IdnaMappingTable.txt`.
 *
 * Comment lines are either blank or start with a `#` character. Lines may also end with a comment.
 * All comments are ignored.
 *
 * Regular lines contain fields separated by semicolons.
 *
 * The first element on each line is a single hex code point (like 0041) or a hex code point range
 * (like 0030..0039).
 *

    * 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).

## 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})
```

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

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

$ 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>

////

 * JavaScript parser `urltestparser.js` with which this class attempts to be compatible.
 *
 * Each line of the `urltestdata.txt` file specifies a test. Lines look like this:
 *
 * ```
 * http://example\t.\norg http://example.org/foo/bar s:http h:example.org p:/
 * ```
 */
class WebPlatformUrlTestData {
  var input: String? = null
  var base: String? = null

          // it is kind of lame that we need to construct a decoder to access this value.
          // if this is a concern we could add special cases for some known charsets (like utf8)
          // or we could avoid inputstreamreader and use the decoder api directly
          // TODO(lukes): in a real implementation we would need to handle overflow conditions
          int maxChars = (int) (size.get().intValue() * cs.newDecoder().maxCharsPerByte());

It is just a function that can take all the same parameters that a *path operation function* can take:

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[8:9] *}

That's it.

**2 lines**.

And it has the same shape and structure that all your *path operation functions* have.

You can think of it as a *path operation function* without the "decorator" (without the `@app.get("/some-path")`).

<img src="/img/tutorial/security/image03.png">

We are not verifying the validity of the token yet, but that's a start already.

## Recap { #recap }

    checkHelperVersion(NO_ATOMIC_FIELD_UPDATER, "SynchronizedAtomicHelper");

    // Then, run the actual tests under each alternative classloader:

    runTestMethod(NO_ATOMIC_FIELD_UPDATER);
    // TODO(lukes): assert that the logs are full of errors
  }

  /**
   * Runs the corresponding {@link FuturesTest} test method in a new classloader that disallows
   * certain core JDK classes.
   */