docs: function uniqStates(states) {
      var seen = {}, a = [], path, i, n;
  
      for (i = 0, n = states.length; i < n; i++) {
        if (!states[i]) { continue; }
        path = states[i].path();
        if (!seen[path]) {
          a.push(states[i]);
          seen[path] = true;
        }
      }
  
      return a;
    }