code: function sinter(/* key-1, key-N, req*/) {
    var args = slice.call(arguments, 0)
      , req = typeof args[args.length-1] === 'object' ? args.pop() : null
      , set = new Set()
      , list
      , src
      , i;
  
    for(i = 0;i < args.length;i++) {
      src = this.getKey(args[i], req);
      if(src === undefined) return [];
      set.sadd(src.data);
    }
  
    list = set.data.slice(0);
  
    function filter(member) {
      for(i = 0;i < args.length;i++) {
        src = this.getKey(args[i]);
        if(!src.sismember(member)) return false;
      }
      return true;
    }
  
    list = list.filter(filter.bind(this));
  
    return list;
  }
docs: Returns the members of the set resulting from the intersection
  of all the given sets.