>>> urls = r'/node/(\d)'
>>> regex = re.compile(urls)
>>> regex.search('/node/122').group()
'/node/1'
>>> regex.search('/node/122').group(1)
'1'

• define the pattern.
• compile, python will return regex object
• use the search method, pass the string we wanna search for.
• match object will be return if the pattern found.
• use .group() method of match object to pull out matching group.