diff --git a/digits-work-sample-go.d/transaction.go b/digits-work-sample-go.d/transaction.go
index dee1f46..1cbbe15 100644
--- a/digits-work-sample-go.d/transaction.go
+++ b/digits-work-sample-go.d/transaction.go
@@ -48,8 +48,11 @@ type Transactions []Transaction
 
 // Sum adds all transactions together.
 func (trns Transactions) Sum() Amount {
-	// TODO: Not implemented.
-	return 0.0
+	result := Amount(0.0)
+	for i := range trns {
+		result += trns[i].Amount
+	}
+	return result
 }
 
 // Count is the number of unique Transactions.
diff --git a/todo.yaml b/todo.yaml
index 8fd05eb..982a922 100755
--- a/todo.yaml
+++ b/todo.yaml
@@ -15,6 +15,8 @@ todo:
     compatilble stuff
   - transaction.go:Transaction:String not clear if FormatUSD or amount currency should
     not be changed, or even what currency Amount is
+  - transaction.go:Transaction:Sum again doesnt care about Amount currency or vendor/vendee
+    drift
 scheduled: []
 done:
 - todo: hello world
@@ -416,3 +418,19 @@ done:
   - my `go mod tidy` actually cleared `go.mod` file, probably weird localhost backwards
     compatilble stuff
   ts: Sun Oct 15 11:24:56 MDT 2023
+- todo: go test
+  subtasks:
+  - TestAnalyzer_TransctionsSum
+  - TestAnalyzer_LargestTransaction
+  - TestAnalyzer_DuplicatesExcluded
+  - TestAnalyzer_GroupByCategory
+  - TestAnalyzer_BigSpendersReport
+  - TestAnalyzer_TransactionsFromURLs
+  - TestAnalyzer_TransactionsFromURLsConcurrent
+  - amount.go:Rounded probably does NOT handle float precision well... it is float64
+    tho...
+  - my `go mod tidy` actually cleared `go.mod` file, probably weird localhost backwards
+    compatilble stuff
+  - transaction.go:Transaction:String not clear if FormatUSD or amount currency should
+    not be changed, or even what currency Amount is
+  ts: Sun Oct 15 11:27:47 MDT 2023