1 files changed, 5 insertions, 1 deletions
diff --git a/lib/sqlalchemy/exceptions.py b/lib/sqlalchemy/exceptions.py
index c803a06c3..16a288503 100644
--- a/lib/sqlalchemy/exceptions.py
+++ b/lib/sqlalchemy/exceptions.py
@@ -28,7 +28,11 @@ class ArgumentError(SQLAlchemyError):
 class TimeoutError(SQLAlchemyError):
     """raised when a connection pool times out on getting a connection"""
     pass
-    
+
+class ConcurrentModificationError(SQLAlchemyError):
+    """raised when a concurrent modification condition is detected"""
+    pass
+        
 class FlushError(SQLAlchemyError):
     """raised when an invalid condition is detected upon a flush()"""
     pass