code: def reply():
      
      params = request.json
      if not params:
          return jsonify({
              "status": "error",
              "error": "Request must be of the application/json type!",
          })
  
      username = params.get("username")
      message  = params.get("message")
      uservars = params.get("vars", dict())
  
      # Make sure the required params are present.
      if username is None or message is None:
          return jsonify({
              "status": "error",
              "error": "username and message are required keys",
          })
  
      # Copy and user vars from the post into RiveScript.
      if type(uservars) is dict:
          for key, value in uservars.items():
              bot.set_uservar(username, key, value)
  
      # Get a reply from the bot.
      reply = bot.reply(username, message)
  
      # Get all the user's vars back out of the bot to include in the response.
      uservars = bot.get_uservars(username)
  
      # Send the response.
      return jsonify({
          "status": "ok",
          "reply": reply,
          "vars": uservars,
      })
docs: Fetch a reply from RiveScript.
  
      Parameters (JSON):
      * username
      * message
      * vars