I am newbie in Python world. creating first web application using python, but getting following error

import web

urls = (
  '/', 'index'
)

app = web.application(urls, globals())

class index:
    def GET(self):
        greeting = "Python welcomes you"
        return greeting

if __name__ == "__main__":
    app.run()

The error message is:

error: No module named 'utils'