fix: Assignment
diff --git a/erpnext/controllers/sales_and_purchase_return.py b/erpnext/controllers/sales_and_purchase_return.py
index 6a03c51..cb68315 100644
--- a/erpnext/controllers/sales_and_purchase_return.py
+++ b/erpnext/controllers/sales_and_purchase_return.py
@@ -25,9 +25,9 @@
ref_doc = frappe.get_doc(doc.doctype, doc.return_against)
if doc.doctype == "Sales Invoice":
- party_type == "customer"
+ party_type = "customer"
else:
- party_type == "supplier"
+ party_type = "supplier"
if ref_doc.company == doc.company and ref_doc.get(pary_type) == doc.get(party_type) and ref_doc.docstatus == 1:
# validate posting date time