Quesitons for importing config_entries

I am new to Home Assistant Development. I created a component under the foloder custom_components. When I follow the tutorial in https://developers.home-assistant.io/docs/config_entries_config_flow_handler to test the ConfigFlow, I copied the following code into my config_flow.py

from homeassistant import config_entries
import voluptuous as vol
from .const import DOMAIN

class ExampleConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
async def async_step_user(self, info):
if info is not None:
pass # TODO: process info
return self.async_show_form(
step_id=“user”, data_schema=vol.Schema({vol.Required(“password”): str})

However, pylint keeps reminding me of the error:

Unable to import ‘homeassistant’.

Did I miss something to configure? Can anyone help me out?