Counts the number of unique object instances within an object. It's slow.

count subobjects

function countObjChildren(thing){
    var visited = [];

    function count(thing){
        for(var key in thing){
            var prop = thing[key];
            if(prop != null && typeof thing[key] === 'object'){
                if(visited.indexOf(prop)<0){
                    visited.push(prop);
                    count(prop);
                }
            }
        }
    }

    count(thing);

    return visited.length;
}