Fix broken sink summation.

diff --git a/ledger.py b/ledger.py
index c7f3116a4748be4ba261a2434cd9ccec71c2ce57..89cf94fca69ad0bebfdcffc5a091951adb2819e9 100755 (executable)
--- a/ledger.py
+++ b/ledger.py
@@ -44,7 +44,7 @@ class Wealth:
         """Drop zero amounts, invert non-zero ones."""
         sink = Wealth()
         for moneys in [Wealth({c: a}) for c, a in self.moneys.items() if a]:
-            sink = moneys
+            sink -= moneys
         return sink