```Python hl_lines="35"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

/// tip

Notice that you are not passing the router itself (`invoices_callback_router`) to `callback=`, but the attribute `.routes`, as in `invoices_callback_router.routes`.

///

### Check the docs

```

### Existing object replication

Existing object replication as detailed [here](https://aws.amazon.com/blogs/storage/replicating-existing-objects-between-s3-buckets/) can be enabled by passing `existing-objects` as a value to `--replicate` flag while adding or editing a replication rule.

#### Running doctest for testable docstring

There are two ways to test the code in the docstring locally:

1.  If you are only changing the docstring of a class/function/method, then you
    can test it by passing that file's path to
    [tf_doctest.py](https://www.tensorflow.org/code/tensorflow/tools/docs/tf_doctest.py).
    For example:

    ```bash
    python tf_doctest.py --file=<file_path>
    ```

    }

    if (isControlFrame && frameLength > PAYLOAD_BYTE_MAX) {
      throw ProtocolException("Control frame must be less than ${PAYLOAD_BYTE_MAX}B.")
    }

    if (isMasked) {
      // Read the masking key as bytes so that they can be used directly for unmasking.
      source.readFully(maskKey!!)
    }
  }

  @Throws(IOException::class)
  private fun readControlFrame() {
    if (frameLength > 0L) {

     */
    open fun <T> tag(
      type: Class<in T>,
      tag: T?,
    ) = commonTag(type.kotlin, tag)

    /**
     * Override the [Request.url] for caching, if it is either polluted with
     * transient query params, or has a canonical URL possibly for a CDN.
     *
     * Note that POST requests will not be sent to the server if this URL is set

Using `UploadFile` has several advantages over `bytes`:

* You don't have to use `File()` in the default value of the parameter.
* It uses a "spooled" file:
    * A file stored in memory up to a maximum size limit, and after passing this limit it will be stored in disk.
* This means that it will work well for large files like images, videos, large binaries, etc. without consuming all the memory.
* You can get metadata from the uploaded file.

        // padding is alwas binary 1 followed by binary 0s
        byte[] tail = new byte[padLen + 8];
        tail[0] = (byte)0x80;

        // append length before final transform:
        // save number of bits, casting the long to an array of 8 bytes
        // save low-order byte first.
        for (int i = 0; i < 8; i++)
            tail[padLen + i] = (byte)((count * 8) >>> (8 * i));

        engineUpdate(tail, 0, tail.length);

If the behavior is threatening or harassing, or for other reasons requires immediate escalation, please see below.

However, for the vast majority of issues, we aim to empower individuals to first resolve conflicts themselves, asking for help when needed, and only after that fails to escalate further. This approach gives people more control over the outcome of their dispute. 

#       space-separated string is a well documented source of bugs and security
#       problems, so this is (mostly) avoided, by progressively accumulating
#       options in "$@", and eventually passing that to Java.
#
#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
#       see the in-line comments for details.
#

   * instead.
   *
   * @since 14.0
   */
  public static UnsignedLong fromLongBits(long bits) {
    // TODO(lowasser): consider caching small values, like Long.valueOf
    return new UnsignedLong(bits);
  }

  /**
   * Returns an {@code UnsignedLong} representing the same value as the specified {@code long}.
   *