The Central Callback type.
This type serves two purposes:
1. Externally, the Serialized object is returned via the `_dash-dependencies` endpoint of a dash application to set up the dash renderer loop
2. Internally, the HandlerFunction of the Callback is evaluated when a qualified call to `_dash-update-component` is performed.
As this type needs dynamic members in addition to the static members created by the default constructor, it is not recommended to use the constructor to create a callback,
but rather the `singleOut` or `multiOut` members.
Creating an instance of this type and registering it on the callback map of the DashApp is the equivalent of the @app.callback decorator in python.