update

src/mcts.jl

@@ -203,14 +203,17 @@ end
 """
 function expand(node::MCTSNode, transition::Function, transitionargs::NamedTuple; 
           totalsample::Integer=3)
-  results = Any[]
+  
+  # not use Any[] because I want to preserve result order
+  results = Vector{Any}(undef, totalsample) 
+
   @sync for i in 1:totalsample
       @spawn begin
-          results[i] = transition(deepcopy(node.state), deepcopy(transitionargs))
+        result = transition(deepcopy(node.state), deepcopy(transitionargs))
+        results[i] = result
       end
-      println("--> sampling $i")
   end
-
+  
   for result in results
     newNodeKey::AbstractString = result[:newNodeKey]
     newstate::AbstractDict = result[:newstate]