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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 get(url, last_modified=None):
 """Performs a get request to a given url. Returns an empty str on error. """

    try:
        with closing(urllib2.urlopen(url)) as page:
            if last_modified is not None:
                last_mod = dateutil.parser.parse(dict(page.info())['last-modified'])
                if last_mod <= last_modified:
                    return ""
            return page.read()
    except urllib2.URLError:
        return ""