ระบุรายละเอียดของลูกค้าที่ไม่มีกรมธรรม์ใดๆ
List the details of the customers who do not have any policies.
{'Customer_Policies': {'customer_id': 'string'}, 'Customers': {'customer_details': 'string', 'customer_id': 'string'}}
customer_id_with_policies = df['Customer_Policies']['customer_id'].unique(); df['Customers'][~df['Customers']['customer_id'].isin(customer_id_with_policies)]['customer_details']