Implement context manager protocol

concert_astor/workspace.py

@@ -25,6 +25,12 @@ class Workspace(object):
     def delete(self):
         self.penny.delete(self.name)
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        self.close()
+
 
 class Penny(object):