Generate JSON file from Python-dict: Convert dict-variables to JSON file

dict2json.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import json

"""
explanation of json-module
json.load(file_obj) : file_obj --> dict
json.loads(json_str) : json_str --> dict
json.dumps(dict) : dict --> json_str
json.dump(dict, file_obj) : write variable-of-dict to JSON file

If json_file contains 2 or more objects, "json.load(file_obj)"　will be to an error.
As JSON-file contains multiple objects, "json.load()" cannot extract 2 or more objects from JSON file at once.
"""

cities = {
        "1": {"rank": 1, "city": "上海", "population": 24150000},
        "2": {"rank": 2, "city": "カラチ", "population": 23500000},
        "3": {"rank": 3, "city": "北京", "population": 21516000},
        "4": {"rank": 4, "city": "天津", "population": 14722100},
        "5": {"rank": 5, "city": "イスタンブル", "population": 14160467}
}

# By mode="w", you can write variables of dict to new file as JSON file. 
with open("output/top_cities.json", mode="w", encoding="utf-8") as f:
    json.dump(cities, f)  # dict to JSON file