old_contents: from flask import Flask, render_template
  from flask_bootstrap import Bootstrap
  
  app = Flask(__name__)
  Bootstrap(app)
  
  
  @app.route('/')
  def index():
      return render_template("index.html")
  
  if __name__ == '__main__':
      app.run(debug=True)
  
new_contents: from flask import Flask, render_template
  from flask_bootstrap import Bootstrap
  from flask.ext.sqlalchemy import SQLAlchemy
  from flask.ext.script import Manager
  from flask.ext.migrate import Migrate, MigrateCommand
  
  import os
  
  app = Flask(__name__)
  app.config['SQLALCHEMY_DATABASE_URI'] = os.environ['DATABASE_URL']
  Bootstrap(app)
  
  db = SQLAlchemy(app)
  migrate = Migrate(app, db)
  
  manager = Manager(app)
  manager.add_command('db', MigrateCommand)
  
  
  @app.route('/')
  def index():
      return render_template("index.html")
  
  
  @manager.command
  def run():
      app.run(debug=True)
  
  if __name__ == '__main__':
      manager.run()
  
subject: Add flask-sqlalchemy/flask-migrate boilerplate