code: function (a, b) {
          var dx = (b[0] - a[0]) * this.kx;
          var dy = (b[1] - a[1]) * this.ky;
          if (!dx && !dy) return 0;
          var bearing = Math.atan2(dx, dy) * 180 / Math.PI;
          if (bearing > 180) bearing -= 360;
          return bearing;
      }
docs: Returns the bearing between two points in angles.
  
  @param {Array<number>} a point [longitude, latitude]
  @param {Array<number>} b point [longitude, latitude]
  @returns {number} bearing
  @example
  var bearing = ruler.bearing([30.5, 50.5], [30.51, 50.49]);
  //=bearing