<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _add_mem_percent(self, cur_read):
 """Compute memory percent utilisation based on the mem_rss_bytes and mem_limit_bytes """

        for executor_id, cur_data in cur_read.items():
            stats = cur_data['statistics']
            mem_rss_bytes = stats.get('mem_rss_bytes')
            mem_limit_bytes = stats.get('mem_limit_bytes')
            if mem_rss_bytes and mem_limit_bytes != 0:
                stats['mem_percent'] = mem_rss_bytes / float(mem_limit_bytes)