def _signing_key(self):
        """
        Returns (bytes):
            An AWS Signature V4 signing key generated from the secret_key, date,
            region, service, and request type.
        """
        key = self._hmac(('AWS4' + self.secret_key).encode('utf-8'), self.datestamp)
        key = self._hmac(key, self.region)
        key = self._hmac(key, self.service)
        key = self._hmac(key, 'aws4_request')
        return key

        Returns (bytes):
            An AWS Signature V4 signing key generated from the secret_key, date,
            region, service, and request type.
        
kafka/sasl/msk.py