first push

Wallet/errors.py

@@ -0,0 +1,10 @@
+from django.db import IntegrityError
+
+
+class InsufficientBalance(IntegrityError):
+    """Raised when a wallet has insufficient balance to
+    run an operation.
+    We're subclassing from :mod:`django.db.IntegrityError`
+    so that it is automatically rolled-back during django's
+    transaction lifecycle.
+    """