input: Write a python function to create a Flask route that returns the current date and time.
  assert 'date_time' in get_routes(app)
  assert isinstance(get_date_time().date(), datetime.date)
  assert isinstance(get_date_time().time(), datetime.time)
output: def get_date_time():
      from flask import Flask
      from datetime import datetime
      
      app = Flask(__name__)
      
      @app.route('/date_time')
      def date_time():
          now = datetime.now()
          return now.strftime("%Y-%m-%d %H:%M:%S")
      
      return app
  
  def get_routes(app):
      return [rule.endpoint for rule in app.url_map.iter_rules()]
  
  def get_date_time():
      from datetime import datetime
      return datetime.now()
  
  app = get_date_time()