Server script problem to create datetime

[NCP]

@Mack

if not doc.custom_ref:
        doc.custom_ref = frappe.utils.now_datetime().strftime('%Y%m%d%H%M%S')

the script worked properly but it did not work in the server script doctype because when you save the doc then faced the ImporrError.

Main issue is:

ImportError: __import__ not found ERPNext

Server scripts run in a restricted context for ensuring security. You can’t import any external python module in server scripts.