Exercise 1: createTask(_:) — A Real POST Request with JSON Body and Response Decoding — Possible Solution
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func createTask(_ newTask: NewTaskRequest) async throws -> Task {
    let url = URL(string: "https://api.example.com/tasks")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.httpBody = try JSONEncoder().encode(newTask)

    let (data, response) = try await URLSession.shared.data(for: request)

    guard let httpResponse = response as? HTTPURLResponse,
          (200..<300).contains(httpResponse.statusCode) else {
        throw APIError.requestFailed(statusCode: (response as? HTTPURLResponse)?.statusCode ?? 0)
    }

    do {
        return try JSONDecoder().decode(Task.self, from: data)
    } catch {
        throw APIError.decodingFailed
    }
}

HOW IT WORKS: A real URLRequest is built with httpMethod set to
"POST" (rather than the implicit GET a plain URL would use), a real
"Content-Type: application/json" header telling the server what
format the body is in, and httpBody set to the JSON-encoded bytes of
newTask via JSONEncoder().encode(newTask) - exactly the chapter's own
Encodable pattern, applied to the specific NewTaskRequest struct
passed into this function.

URLSession.shared.data(for: request) - the request-based overload,
not the URL-based data(from:) Fundamentals used - sends the fully
configured request, including its method, header, and body. The
response is checked against the real 200..<300 success range (per the
chapter's own reasoning that a real server might return 200, 201, or
another 2xx code, not only exactly 200), throwing a real, specific
APIError.requestFailed with the actual status code on failure.

On success, the response body - presumably the newly created task,
echoed back by the server with its own assigned real id - is decoded
into a Task using the same JSONDecoder/do-catch/decodingFailed pattern
established elsewhere in this chapter.

ANSWER: createTask(_:) builds a real POST URLRequest with a JSON-
encoded body via JSONEncoder, sends it with
URLSession.shared.data(for:), checks the real 200..<300 success range,
and decodes the server's response into a Task - correctly combining
this chapter's own Encodable, URLRequest, and error-handling patterns
into one complete networking function.

WHY THIS WORKS AS AN ANSWER
------------------------------
This correctly assembles every real technique the chapter covered
(URLRequest configuration, Encodable body encoding, range-based status
checking, and structured error throwing) into one cohesive, real POST
function.