diff --git a/Exercises/exercise-2/Solution.hs b/Exercises/exercise-2/Solution.hs
index 1f3cd25..0de6b48 100644
--- a/Exercises/exercise-2/Solution.hs
+++ b/Exercises/exercise-2/Solution.hs
@@ -63,6 +63,7 @@ zoe = Car {
 sorted = sort [zoe, ferrari, ford]
 -- >>> sorted
 -- [Car {model = Model "Fiesta", make = Make "Ford", year = 2017, color = RGB {r = 255, g = 0, b = 0}, power = 70},Car {model = Model "Testarossa", make = Make "Ferrari", year = 1991, color = RGB {r = 0, g = 255, b = 0}, power = 27},Car {model = Model "Zoe", make = Make "Renault", year = 2023, color = RGB {r = 255, g = 255, b = 255}, power = 70}]
+--
 
 --------------------
 -- Exercise 2
@@ -104,6 +105,7 @@ tree =
 
 -- >>> show tree
 -- "PolyTree 1 [PolyTree 2 [PolyTree 5 [],PolyTree 6 [],PolyTree 7 []],PolyTree 3 [PolyTree 8 []]]"
+--
 
 --------------------
 -- Exercise 3
@@ -121,8 +123,10 @@ eval x =
 
 -- >>> Z
 -- Z
+--
 -- >>> eval $ S $ S $ S Z
 -- 3
+--
 
 uneval :: Integer -> NatNumber
 uneval x
@@ -131,13 +135,19 @@ uneval x
     | otherwise = S (uneval (x - 1))
 
 -- >>> uneval (-1)
--- negative numbers are not natural numbers
+-- *** Exception: negative numbers are not natural numbers
+-- CallStack (from HasCallStack):
+--   error, called at /home/manuel/Documents/Repositories/zhaw-fup/Exercises/exercise-2/Solution.hs:133:15 in main:Main
+--
 -- >>> uneval 0
 -- Z
+--
 -- >>> uneval 1
 -- S Z
+--
 -- >>> uneval 3
 -- S (S (S Z))
+--
 
 addNat :: NatNumber -> NatNumber -> NatNumber
 addNat a b =
@@ -147,6 +157,7 @@ addNat a b =
 
 -- >>> eval (addNat (uneval 7) (uneval 2))
 -- 9
+--
 
 mulNat :: NatNumber -> NatNumber -> NatNumber
 mulNat a b =
@@ -156,6 +167,7 @@ mulNat a b =
 
 -- >>> eval (mulNat (uneval 3) (uneval 2))
 -- 6
+--
 
 fact :: NatNumber -> NatNumber
 fact x =
@@ -165,8 +177,10 @@ fact x =
 
 -- >>> eval (fact Z)
 -- 1
+--
 -- >>> eval (fact (S (S Z)))
 -- 2
+--
 
 --------------------
 -- Exercise 4
@@ -203,3 +217,4 @@ fibProgram =
 -- Should evaluate to True
 -- >>> sum (execute fibProgram 31250) == 26183978971946924
 -- True
+--