Python处理Dict生成json-PHP中国語ネットワークQ&A

情况是这样：
json文件中存在一个值为

"headers":{
    "connection":["close"],
    "content_language":["en"],
    "content_length":["3137"],
    "content_type":["text/html"],
    "server":["squid/3.1.23"],
    "unknown":[
      {"key":"mime_version","value":["1.0"]},
      {"key":"date","value":["Sat, 25 Mar 2017 06:11:38 GMT"]},
      {"key":"x_squid_error","value":["ERR_INVALID_URL 0"]},
      {"key":"x_cache","value":["MISS from unknown"]},
      {"key":"x_cache_lookup","value":["NONE from unknown:8080"]}
    ]
}

由于之前的脚本的处理过于简单粗暴。现实要将"unknown"给替换成字典中的值。
以下是我处理的一段Test code ，在Ipython中：

import json
f = open('file.json','r')
test_line = f.readline()
jsonstr = json.loads(test_line)

he = jsonstr['headers']
# 输出正常的
for (k,v) in he.items():
    print k,':',v[0]

输出的是：

    "connection":"close",
    "content_language":"en",
    "content_length":"3137",
    "content_type":"text/html",
    "server":"squid/3.1.23",
    "unknown":[
      {"value":["1.0"],"key":"mime_version"}

问题：
1，怎么处理“unknown”中的list，用for的话，怎么输出？
2，怎么处理“unknown”使其能输出如下的结果：

    "connection":"close",
    "content_language":"en",
    "content_length":"3137",
    "content_type":"text/html",
    "server":"squid/3.1.23",
    "mime_version"："1.0",
    "date":"Sat, 25 Mar 2017 06:11:38 GMT",
    "x_squid_error":"ERR_INVALID_URL 0",
    "x_cache":"MISS from unknown",
    "x_cache_lookup":"NONE from unknown:8080"

谢谢！～