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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def url_to_string(url):
 """ Return the contents of a web site url as a string. """

    try:
        page = urllib2.urlopen(url)
    except (urllib2.HTTPError, urllib2.URLError) as err:
        ui.error(c.MESSAGES["url_unreachable"], err)
        sys.exit(1)

    return page