docs: function distance(from, to) {
    const degrees2radians = Math.PI / 180;
    const dLat = degrees2radians * (to[1] - from[1]);
    const dLon = degrees2radians * (to[0] - from[0]);
    const lat1 = degrees2radians * from[1];
    const lat2 = degrees2radians * to[1];
  
    const a = Math.pow(Math.sin(dLat / 2), 2) +
          Math.pow(Math.sin(dLon / 2), 2) * Math.cos(lat1) * Math.cos(lat2);
    return Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  }