Making a field in a django admin form visible or invisible depending on the user

admin.py

from django.contrib import admin
from books.models import Agent, PolicyIssue

class PolicyIssueAdmin(admin.ModelAdmin):
 
    def add_view(self, request, form_url='', extra_context=None):
        if request.user.get_profile().is_employee:
            self.model.branch.field.editable = False
        else:
            self.model.branch.field.editable = True
        return super(PolicyIssueAdmin, self).add_view(request, form_url)

admin.site.register(PolicyIssue, PolicyIssueAdmin)