code: function(point) {
        var d2r = Math.PI / 180.0;
        var lat1rad = this.latitude * d2r;
        var long1rad = this.longitude * d2r;
        var lat2rad = point.latitude * d2r;
        var long2rad = point.longitude * d2r;
        var deltaLat = lat1rad - lat2rad;
        var deltaLong = long1rad - long2rad;
        var sinDeltaLatDiv2 = Math.sin(deltaLat / 2);
        var sinDeltaLongDiv2 = Math.sin(deltaLong / 2);
        // Square of half the straight line chord distance between both points.
        var a = ((sinDeltaLatDiv2 * sinDeltaLatDiv2) +
                 (Math.cos(lat1rad) * Math.cos(lat2rad) *
                  sinDeltaLongDiv2 * sinDeltaLongDiv2));
        a = Math.min(1.0, a);
        return 2 * Math.asin(Math.sqrt(a));
      }
docs: Returns the distance from this GeoPoint to another in radians.
  @param {Parse.GeoPoint} point the other Parse.GeoPoint.
  @return {Number}