TypeError: Parameters to generic types must be types. Got slice(<class 'str'>, typing.Union[typing.Dict, typing.List[typing.Dict]], None)

Hello,

I was following the instruction from rasa website and had an error saying"TypeError: Parameters to generic types must be types. Got slice(<class ‘str’>, typing.Union[typing.Dict, typing.List[typing.Dict]], None).". It seems there is an error in slot_mappings function and no idea how to fix it. This has bothered me for a long time and really appreciate your help.

This is from actions.py:

from typing import Dict, Text, Any, List, Union, Optional, Tuple from rasa_sdk import Action, Tracker from rasa_sdk.executor import CollectingDispatcher from rasa_sdk.forms import FormAction from rasa_sdk import Action from rasa_sdk.events import UserUtteranceReverted import typing

class SalesForm(FormAction): “”“Collects sales information and adds it to the spreadsheet”“”

def name(self) -> Text:
    return "sales_form"

@staticmethod
def required_slots(tracker) -> List[Text]:
    return [
        "job_function",
        "use_case",
        "budget",
        "person_name",
        "company",
        "business_email",
        ]

def slot_mappings(self) -> Dict[Text: Union[Dict, List[Dict]]]:
# type: () -> Dict[Text: Union[Dict, List[Dict]]]
"""A dictionary to map required slots to
- an extracted entity
- intent: value pairs
- a whole message
or a list of them, where a first match will be picked"""
   return {"use_case": self.from_text(intent="inform")}


def submit(
        self,
        dispatcher: CollectingDispatcher,
        tracker: Tracker,
        domain: Dict[Text, Any],
    ) -> List[Dict]:

    dispatcher.utter_message("Thanks for getting in touch, we’ll contact you soon")
    return []

The error message after “rasa run actions”:

(rasa) C:\rasa-assistant_1>rasa run actions

TypeError: Parameters to generic types must be types. Got slice(<class ‘str’>, typing.Union[typing.Dict, typing.List[typing.Dict]], None).

The website of rasa instruction:

ah! sorry about that, that’s a typo in the docs, I’ve created a PR to fix that (which should also show you how to fix the problem)