code: function updateTaxis()
  {
      var ids = [ "11", "22", "33" ];
      var statuses = [ "avail", "busy", "scheduled" ];
      var bbox = bkutils.geoBoundingBox(center[0], center[1], 2); // within 2 km from the center
      var latitude = lib.randomNum(bbox[0], bbox[2], 5);
      var longitude = lib.randomNum(bbox[1], bbox[3], 5);
      var id = ids[lib.randomInt(0, ids.length - 1)];
      var status = statuses[lib.randomInt(0, statuses.length - 1)];
  
      db.put("taxi", { id: id, status: status, latitude: latitude, longitude: longitude });
  }
docs: Simulate taxi location changes