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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 http_session(self):
 """HTTP Session property :return: vk_requests.utils.VerboseHTTPSession instance """

        if self._http_session is None:
            session = VerboseHTTPSession()
            session.headers.update(self.DEFAULT_HTTP_HEADERS)
            self._http_session = session
        return self._http_session