[minor] imported cstr in selling_controller
diff --git a/controllers/selling_controller.py b/controllers/selling_controller.py
index 320ad2f..086c42e 100644
--- a/controllers/selling_controller.py
+++ b/controllers/selling_controller.py
@@ -3,7 +3,7 @@
from __future__ import unicode_literals
import webnotes
-from webnotes.utils import cint, flt, comma_or, _round, add_days
+from webnotes.utils import cint, flt, comma_or, _round, add_days, cstr
from setup.utils import get_company_currency
from selling.utils import get_item_details
from webnotes import msgprint, _