HTTP is text exchanged in pairs. A request has a method, a path, headers and an optional body. A response has a status code, headers and a body.

• GET reads, POST creates, PUT replaces, DELETE removes.
• 2xx means success, 4xx a client mistake, and 5xx a server failure.
• Content-Type says how to interpret the body.

Most APIs send JSON. The json module converts between JSON text and Python values.

import json

text = json.dumps({"id": 1, "ok": True})
print(text)  # {"id": 1, "ok": true}
data = json.loads(text)
print(data["ok"])  # True

• None becomes null, and tuples become arrays.
• Dict keys become strings, so {1: "a"} returns as {"1": "a"}.
• Types with no JSON form, such as a set, raise TypeError.
• Bad input raises json.JSONDecodeError, a subclass of ValueError.

Write make_response(data, status=200) returning a dict with status, headers ({"Content-Type": "application/json"}) and body as compact JSON text with sorted keys. Write read_response(response) returning the parsed body, raising ValueError for status 400 or above (including the body's error value if it has one) or for invalid JSON.

The explanation opens here once every check passes.