python 使用 with open（） as 读写文件

'''
有一个数据list of dict如下
a = [
    {"yoyo1": "123456"},
    {"yoyo2": "123456"},
    {"yoyo3": "123456"},
]
写入到本地一个txt文件，内容格式如下：
yoyo1,123456
yoyo2,123456
yoyo3,123456
'''
a = [
    {"yoyo1": "123456"},
    {"yoyo2": "123456"},
    {"yoyo3": "123456"},
]
with open('a.txt','w+') as f:
    for i in a:
        for key ,value in i.items():   #字典items() 方法以列表返回可遍历的(键, 值) 元组数组。
            f.write("{},{} {}".format(key,value,'\n'))   #
with open('a.txt','r') as f:
    print(f.read())