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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 validate_url(cls, url):
 """Strip and trailing slash to validate a url :param url: the url address :return: the valid url address :rtype: string """


        if url is None:
            return None

        url = url.strip()
        while url.endswith('/'):
            url = url[:-1]
        return url