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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 open(self, url):
 """ Open a document at the specified URL. The document URL's needs not contain a protocol identifier, and if it does, that protocol identifier is ignored when looking up the store content. Missing documents referenced using the internal 'suds' protocol are reported by raising an exception. For other protocols, None is returned instead. @param url: A document URL. @type url: str @return: Document content or None if not found. @rtype: bytes """

        protocol, location = self.__split(url)
        content = self.__find(location)
        if protocol == 'suds' and content is None:
            raise Exception, 'location "%s" not in document store' % location
        return content