text: #!/usr/bin/python3
  
  from flask import Flask
  from flask_sqlalchemy import SQLAlchemy
  
  app = Flask(__name__)
  
  app.config['SQLALCHEMY_DATABASE_URI'] = "mysql+pymysql://waled:root@localhost/data"
  app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
  db = SQLAlchemy(app)
  
  class Countries(db.Model):
      id = db.Column(db.Integer, primary_key=True)
      name = db.Column(db.String(30), nullable=False)
      cities = db.relationship('Cities', backref='country')
  
  class Cities(db.Model):
      id = db.Column(db.Integer, primary_key=True)
      name = db.Column(db.String(30), nullable=False)
      country_id = db.Column(db.Integer, db.ForeignKey('countries.id'), nullable=False)
  
  if __name__=='__main__':
      app.run(debug==True, host='0.0.0.0')
  
  