Flask: How to use app context inside blueprints?

I'm learning flask and python and cannot wrap my head around the way a typical flask application needs to be structured.

I need to access the app config from inside blueprint. Something like this

#blueprint.py
from flask import Blueprint

sample_blueprint = Blueprint("sample", __name__)

# defining a route for this blueprint
@sample_blueprint.route("/")
def index():
     # !this is the problematic line
     # need to access some config from the app
     x = app.config["SOMETHING"]
     # how to access app inside blueprint?

If importing app in blueprint is the solution, will this not result in circulat imports? i.e importing blueprint in app, importing app in blueprints?