anchor.diff:    }
     
     bool validPaymentPath (BoardLoc loc, Card card, CardDirection playedDir, int playerNum, PaymentPath path){
  -    if (path == null || path.length < 2) => false;
  +    if(path == null || path.length < 2) return false;
       
       //validate connection to start of path
       bool connectsToPath = CardUtil.allDirections.any((dir) =>
  
positive.code:   static Set<BoardLoc> _dykstraConnections(Board board, Set<BoardLoc> seen, Set<BoardLoc> fringe){
      //if fringe is empty, return
      if(fringe.length == 0) return seen;
      var first = fringe.first;
      fringe.remove(first);
      seen.add(first);
  
negative.code:   }
  
    bool pathIsConnected(PaymentPath path) {
      if(path.length < 2) return true;
      //(first, rest)
      BoardLoc first = path.removeAt(0);
      
  