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diff --git a/Haskell-book/15/semigroup/src/Trivial.hs b/Haskell-book/15/semigroup/src/Trivial.hs
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+++ b/Haskell-book/15/semigroup/src/Trivial.hs
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+module Trivial where
+
+import Data.Semigroup
+import Test.QuickCheck
+
+data Trivial = Trivial deriving (Eq, Show)
+
+instance Semigroup Trivial where
+    _ <> _ = Trivial
+
+instance Arbitrary Trivial where
+    arbitrary = return Trivial
+
+instance Monoid Trivial where
+    mempty = undefined
+    mappend = (<>)