ef METHOD_NAME(self, method='', canonical_uri='', canonical_query_string='', body='', epoch_t='',
                            algorithm='', host='', service='', region=''):
   """Generates string_to_sign for authorization key generation."""
   canonical_request = self.create_canonical_request(method, canonical_uri,canonical_query_string,
                                                body, epoch_t, host)
   credential_scope = self.get_date(epoch_t) + '/' + \
       region + '/' + service + '/' + 'aws4_request'
   string_to_sign = algorithm + '\n' + self.get_amz_timestamp(epoch_t) + '\n' + credential_scope \
       + '\n' + hashlib.sha256(canonical_request.encode('utf-8')).hexdigest()
   return string_to_sign