diff --git a/Manifest.toml b/Manifest.toml
index 6e1d586..8c75035 100644
--- a/Manifest.toml
+++ b/Manifest.toml
@@ -214,7 +214,7 @@ deps = ["Random"]
 uuid = "9fa8497b-333b-5362-9e8d-4d0656e87820"
 
 [[deps.GeneralUtils]]
-deps = ["DataStructures", "Dates", "Distributions", "JSON3", "MQTTClient", "Random", "Revise", "UUIDs"]
+deps = ["CSV", "DataFrames", "DataStructures", "Dates", "Distributions", "JSON3", "MQTTClient", "Random", "Revise", "UUIDs"]
 path = "/appfolder/app/privatejuliapkg/GeneralUtils"
 uuid = "c6c72f09-b708-4ac8-ac7c-2084d70108fe"
 version = "0.1.0"
diff --git a/src/interface.jl b/src/interface.jl
index bd82554..c42ab8a 100644
--- a/src/interface.jl
+++ b/src/interface.jl
@@ -23,7 +23,7 @@ using LLMMCTS, GeneralUtils
     A number to limit how many attempt will be made.
   
 # Return
-  - `(response, errormsg, success)::NamedTuple`
+  - `(response, errormsg, success)::@NamedTuple{response::String, errormsg::String, success::Bool}`
     if success=`true`, response is a valid JSON string. otherwise, check errormsg. 
 
 # Example
@@ -91,8 +91,8 @@ julia> println(result)
 
 # Signature
 """
-function jsoncorrection(jsonstring::T, example::String, commfunction::Function; 
-                        maxattempt=3)::NamedTuple where {T<:AbstractString}
+function jsoncorrection(jsonstring::T, example::String, commfunction::Function; maxattempt=3
+  )::@NamedTuple{response::String, errormsg::String, success::Bool} where {T<:AbstractString}
 
   initialstate = Dict{Symbol, Any}(
     :reward=> 0,
@@ -116,9 +116,9 @@ function jsoncorrection(jsonstring::T, example::String, commfunction::Function;
                           totalsample=1, maxdepth=(maxattempt-1), maxiterations=1, explorationweight=1.0)
 
   if result[:isterminal] == true
-    return (response=result[:code], errormsg=nothing, success=true)
+    return (response=result[:code], errormsg="nothing", success=true)
   else
-    return (response=nothing, errormsg=result[:errorexplain], success=false)
+    return (response="nothing", errormsg=result[:errorexplain], success=false)
   end
 end