def _order_params(self, data):
        """Convert params to list with signature as last element

        :param data:
        :return:

        """
        has_signature = False
        params = []
        for key, value in data.items():
            if key == 'signature':
                has_signature = True
            else:
                params.append((key, value))
        # sort parameters by key
        params.sort(key=itemgetter(0))
        if has_signature:
            params.append(('signature', data['signature']))
        return params