typeHintStack[typeHintStack.size - 1] = value
    }

  /** Names leading to the current location in the ASN.1 document. */
  private val path = mutableListOf<String>()

  /**
   * False unless we made a recursive call to [write] at the current stack frame. The explicit box
   * adapter can clear this to synthesize non-constructed values that are embedded in octet strings.
   */
  var constructed = false

  fun write(

          # retainVersions: 5 # keep the latest 5 versions of the object including delete markers.

  notify:
    endpoint: https://notify.endpoint # notification endpoint to receive job completion status
    token: Bearer xxxxx # optional authentication token for the notification endpoint
  
  retry:
    attempts: 10 # number of retries for the job before giving up

## The normal **FastAPI** app { #the-normal-fastapi-app }

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

This part is pretty normal, most of the code is probably already familiar to you:

# `UploadFile` class

You can define *path operation function* parameters to be of the type `UploadFile` to receive files from the request.

You can import it directly from `fastapi`:

```python
from fastapi import UploadFile
```

::: fastapi.UploadFile
    options:
        members:
            - file
            - filename
            - size
            - headers
            - content_type
            - read

import okhttp3.mockwebserver.MockWebServer;
import okhttp3.mockwebserver.RecordedRequest;
import okio.ByteString;

/**
 * Runs a MockWebServer on localhost and uses it as the backend to receive an OAuth session.
 *
 * <p>Clients should call {@link #start}, {@link #newAuthorizeUrl} and {@link #close} in that order.
 * Clients may request multiple sessions.
 */

# "/path/bar". This script uses "gsutil rsync" instead, which acts on directory
# contents. About arguments to gsutil:
# "gsutil -m rsync" runs in parallel.
# "gsutil rsync -r" is recursive and makes directories work.
# "gsutil rsync -d" is "sync and delete files from destination if not present in source"

DOWNLOADS="$(mktemp -d)"
mkdir -p "$DOWNLOADS"

import org.apache.maven.project.inheritance.AbstractProjectInheritanceTestCase;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * A test which demonstrates maven's recursive inheritance where
 * a distinct value is taken from each parent contributing to
 * the final model of the project being assembled. There is no
 * overriding going on amongst the models being used in this test:

                sendrecv(bind);
            } catch (final IOException ioe) {
                this.state = 0;
                throw ioe;
            }
        }
    }

    /**
     * Send and receive a DCE/RPC message
     *
     * @param msg
     *            the message to send
     * @throws DcerpcException
     *            if there is a DCE/RPC protocol error
     * @throws IOException

     */
    int DEFAULT_RESPONSE_TIMEOUT = 30000;
    /**
     * Default socket timeout in milliseconds.
     */
    int DEFAULT_SO_TIMEOUT = 35000;
    /**
     * Default receive buffer size for SMB transport.
     */
    int DEFAULT_RCV_BUF_SIZE = 0xFFFF;
    /**
     * Default send buffer size for SMB transport.
     */
    int DEFAULT_SND_BUF_SIZE = 0xFFFF;
    /**

There you can select "Releases only".

By doing it, you will receive notifications (in your email) whenever there's a new release (a new version) of **FastAPI** with bug fixes and new features.

## Connect with the author { #connect-with-the-author }