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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def list_devices():
 """ List devices via HTTP GET. """

    output = {}
    for device_id, device in devices.items():
        output[device_id] = {
            'host': device.host,
            'state': device.state
        }
    return jsonify(devices=output)