update

src/interface.jl

@@ -331,27 +331,35 @@ end
     a game state
   
 # Return
-  - `(isterminal, reward)::Tuple{Bool, Number}`
+  - `(isterminalstate, reward)::Tuple{Bool, <:Number}`
 
 # Example
 ```jldoctest
 julia> 
 ```
 
-# TODO
-  - [x] update docstring
-  - [TESTING] implement the function
-
 # Signature
 """
-function isterminal(state::T)::Tuple{Bool, Number} where {T<:AbstractDict}
+function isterminal(state::T)::Tuple{Bool, <:Number} where {T<:AbstractDict}
   latestObservationKey, _ = GeneralUtils.findHighestIndexKey(state[:thoughtHistory], "Observation")
   latestObservation = state[:thoughtHistory][latestObservationKey]
 
-  # terminal condition is when the user select wine by putting <<winename>> in latest observation 
-  if occursin("<<", latestObservation) && occursin(">>", latestObservation)
-    return true, 1
+  if latestObservation !== nothing
+
+    # terminal condition is when the user select wine by putting <<winename>> in latest observation 
+    if occursin("<<", latestObservation) && occursin(">>", latestObservation)
+      isterminalstate = true
+      reward = 1
+    else
+      isterminalstate = false
+      reward = 0
+    end
+  else
+    isterminalstate = false
+    reward = 0
   end
+
+  return (isterminalstate, reward)
 end