How to connect my PostreSQL DB to Python on Ubuntu linux?

Question

Python

I shoveled everything I could but could not find anything that would explain how to do it.
How to connect the database that I created under my main account to python, that is, how to set the path to this database when I connect it? What needs to be changed here:

from flask import Flask, render_template
import postgresql

db = postgresql.open('postgresql://user:[email protected]/user') 
app = Flask(__name__)

@app.route('/')
def main():
    return 'Hello world'

if __name__ == '__main__':
  app.run(debug=True)