import json
a = [
    {'username': "dev_1009048", 'password': "e60be16cbfeebdb4d4c7dd7c0a6f2f67", 'nickname': "", 'avatar': ""},
    {'username': "dev_1009049", 'password': "e60be16cbfeebdb4d4c7dd7c0a6f2f67", 'nickname': "", 'avatar': ""},
    {'username': "dev_1009050", 'password': "e60be16cbfeebdb4d4c7dd7c0a6f2f67", 'nickname': "", 'avatar': ""}
]
b = json.dumps(a)
print(b)