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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 _uri(self, url):
 """Returns request absolute URI"""

        if url and not url.startswith('/'):
            # Then this must be a proxy request.
            return url
        uri = "{0}://{1}{2}{3}".format(
            self._protocol,
            self.real_connection.host,
            self._port_postfix(),
            url,
        )
        return uri