Sign Instance
GET /data/api/signs/70/?format=api
https://labasi.acdh.oeaw.ac.at/data/api/signs/70/?format=api", "sign_name": "ÚR", "abz_number": "203", "meszl_number": "341", "image_1": "https://labasi.acdh.oeaw.ac.at/media/sign_img/sign_203.jpg", "image_2": null }{ "url": "