<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _sort_to_str(self):
 """ Before exec query, this method transforms sort dict string from {"name": "asc", "timestamp":"desc"} to "name asc, timestamp desc" """


        params_list = []
        timestamp = ""

        for k, v in self._solr_params['sort'].items():
            if k != "timestamp":
                params_list.append(" ".join([k, v]))
            else:
                timestamp = v

        params_list.append(" ".join(['timestamp', timestamp]))

        self._solr_params['sort'] = ", ".join(params_list)