diff --git a/src/mcts.jl b/src/mcts.jl
index 220a019..cfdd446 100644
--- a/src/mcts.jl
+++ b/src/mcts.jl
@@ -204,7 +204,10 @@ end
     contain Thought, Action, Observation
 
 # Return
-  - `newstate::AbstractDict`
+  - (newStatekey, )
+  - `newStatekey::String`
+    key for newstate
+  - `newstate::Dict{Symbol, Any}`
     next game state
 
 # Example
@@ -233,7 +236,7 @@ julia>  thoughtDict = Dict(
 # Signature
 """
 function MCTStransition(a::T1, state::T2, 
-            thoughtDict::T3)::AbstractDict where {T1<:agent, T2<:AbstractDict, T3<:AbstractDict}
+  thoughtDict::T3)::Tuple{String, Dict{Symbol, Any}} where {T1<:agent, T2<:AbstractDict, T3<:AbstractDict}
   latestThoughtKey, _ = GeneralUtils.findHighestIndexKey(thoughtDict, "Thought")
   latestActionKey, latestActionIndice = GeneralUtils.findHighestIndexKey(thoughtDict, "Action")
   _action = thoughtDict[latestActionKey]