class_docstr: A custom REST http input channel that responds using a callback server.
  
  Incoming messages are received through a REST interface. Responses
  are sent asynchronously by calling a configured external REST endpoint.
class_docstr_tok: ["A","custom","REST","http","input","channel","that","responds","using","a","callback","server",".","Incoming","messages","are","received","through","a","REST","interface",".","Responses","are","sent","asynchronously","by","calling","a","configured","external","REST","endpoint","."]
code: def __init__(self, endpoint: EndpointConfig) -> None:
      self.callback_endpoint = endpoint
  
file_path: rasa/rasa/core/channels/callback.py
imports: import logging
  from typing import Text, Dict, Optional, Callable, Awaitable, Any
  from sanic import Blueprint, response
  from sanic.request import Request
  from rasa.core.channels.channel import CollectingOutputChannel, UserMessage, InputChannel
  from rasa.core.channels.rest import RestInput
  from rasa.utils.endpoints import EndpointConfig, ClientResponseError
  from sanic.response import HTTPResponse
label_desc: Use image node_id 3 to create a new CallbackInput object from inherited base classes: RestInput with example: obj = CallbackInput(endpoint)