Override validate function & employee.list

There is a function validate on erpnext/erpnext/hr/doctype/employee.py I want to add more status on validate function. But, I do not want to do it directly on that file since it will modify source code and it will give me problem when I upgrade.

validate_status(self.status, [“Active”, “Temporary Leave”, “Left”])

I want to add some more status & modify employee.list to change color indicator of new status

help me please

Did you find a way to do this ?