Python解析路由器MAC地址：处理单/多MAC及无MAC场景

我正在解析路由器输出数据，需要处理三种场景：单个MAC地址、两个重复MAC地址、无MAC地址。目前的处理代码在应对这些场景时存在问题，以下是相关信息，寻求正确的处理方案：

现有处理代码 #

else: #Starts the parse
    parser5 = ttp(output5, template_05_ad)
    parser5.parse()
    #put result in JSON format
    results_0 = parser5.result(format='json')[0]
    #str to list **convert with json.loads
    result_0 = json.loads(results_0)

    #Places the results into variables
    if 'mac' in result_0[0][0]:
        mac_connected = str(result_0[0][0]['mac'])
    elif 'mac' in result_0[0]:
        mac_connected = str(result_0[0]['mac'])
    else:
        mac_connected = 'NULL'

路由器输出样例 #

One MAC:
                                                             CE 
Vlan     Mac Address       Type        Interface      CTag  Vlan
----  -----------------  ---------  ----------------  ----  ----
4065  E1:B4:19:64:1B:51  Dynamic    10/0/1@1/2/2      na    na  
Total MAC addresses for this criterion: 1

Two MAC:
                                                             CE 
Vlan     Mac Address       Type        Interface      CTag  Vlan
----  -----------------  ---------  ----------------  ----  ----
4065  E1:B4:19:64:1B:51  Dynamic    10/0/1@1/2/2      na    an  
4065  E1:B4:19:64:1B:51  Dynamic    10/0/1@1/2/2      na    na  
Total MAC addresses for this criterion: 1

No MAC:
No MAC addresses found for this criterion

解析后result_0结构 #

One MAC::
[{'mac': 'E1:B4:19:64:1B:51'}]

Two MAC:
[[{'mac': 'E1:B4:19:64:1B:51'}, {'mac': 'E1:B4:19:64:1B:51'}]]

No MAC:
[{}]

需要修正代码，确保在三种场景下都能正确处理：单个MAC时提取该地址，重复MAC时返回唯一值，无MAC时返回'NULL'。

内容的提问来源于stack exchange，提问作者ankou