diff --git a/src/interface.jl b/src/interface.jl
index c802b60..f48efa8 100644
--- a/src/interface.jl
+++ b/src/interface.jl
@@ -32,7 +32,7 @@ using ..type, ..mcts, ..util
     aggressively explore new state.
 
 # Return
-  - `(bestNextState, BestFinalState)::@NamedTuple{bestNextState::T, bestFinalState::T}`
+  - `NamedTuple{(:bestNextState, :bestFinalState), Tuple{T, T}}`
     the best next state and the best final state
 
 # Example
@@ -49,7 +49,7 @@ function runMCTS(
   maxdepth::Integer=3, 
   maxiterations::Integer=10, 
   explorationweight::Number=1.0,
-  )::@NamedTuple{bestNextState::T, bestFinalState::T} where {T<:Any}
+  )::NamedTuple{(:bestNextState, :bestFinalState), Tuple{T, T}} where {T<:Any}
   
   root = MCTSNode("root", initialstate, 0, 0, 0, 0, false, nothing, Dict{String, MCTSNode}())
 
diff --git a/src/mcts.jl b/src/mcts.jl
index fcbb0a6..ad2dd1a 100644
--- a/src/mcts.jl
+++ b/src/mcts.jl
@@ -196,11 +196,6 @@ end
 # Return
   - None
 
-# Example
-```jldoctest
-julia> 
-```
-
 # Signature
 """
 function expand(node::MCTSNode,transition::Function, transitionargs::NamedTuple; 
@@ -249,13 +244,14 @@ end
     Total number to sample from the current node (i.e. expand new node horizontally)
     
 # Return
-  - `(simTrajectoryReward, terminalstate)::Union{Tuple{Number, Dict{Symbol, <:Any}}, Tuple{Number, Nothing}}`
+  - `::NamedTuple{(:simTrajectoryReward, :terminalstate), Tuple{Number, Union{Dict{Symbol, Any}, Nothing}}}`
 
 # Signature
 """
 function simulate(node::MCTSNode, transition::Function, transitionargs::NamedTuple; 
   maxdepth::Integer=3, totalsample::Integer=3
-  )::Union{Tuple{Number, Dict{Symbol, <:Any}}, Tuple{Number, Nothing}}
+)::NamedTuple{(:simTrajectoryReward, :terminalstate), Tuple{Number, Union{Dict{Symbol, Any}, Nothing}}}
+
   simTrajectoryReward = 0.0
   terminalstate = nothing
   
@@ -271,7 +267,7 @@ function simulate(node::MCTSNode, transition::Function, transitionargs::NamedTup
     end
   end
 
-  return (simTrajectoryReward, terminalstate)
+  return (simTrajectoryReward=simTrajectoryReward, terminalstate=terminalstate)
 end