code: def api_routes(self, callsign: str) -> Tuple[Airport, ...]:
          
          from .. import airports
  
          c = requests.get(
              f"https://opensky-network.org/api/routes?callsign={callsign}"
          )
          if c.status_code == 404:
              raise ValueError("Unknown callsign")
          if c.status_code != 200:
              raise ValueError(c.content.decode())
          json = c.json()
  
          return tuple(airports[a] for a in json["route"])
docs: Returns the route associated to a callsign.