bin/dbstore/node_club_dev/system.js/hammingDistance.bson
+ _id hammingDistance
value function (a, b) {
if (typeof(a) === "undefined" || typeof(b) === "undefined") return 64;
var aa = a.split("");
var bb = b.split("");
var count = 0;
for (var i = 0; i < aa.length; i++) if (aa[i] !== bb[i]) count++;
return count;
}