Permissions to Django Admin Actions

I have written some custom actions for my django project, however cannot work out how to make them available to only superusers. I have tried putting an if statement round the actions line with Users.is_superuser but it keeps giving me an error saying there is no attribute called is_superuser.

Here is my admin.py file:

from django.contrib import admin
from models import Art, Agent, UserProfile
from django.contrib import admin
from django.contrib.auth.models import Group, User, AbstractUser
from django.contrib.auth import *
from import_export import resources
from import_export.admin import ImportExportModelAdmin

#admin.site.unregister(Group)

def approve_art(modeladmin, request, queryset):
    queryset.update(authenticate = "approved")

def reject_art(modeladmin, request, queryset):
    queryset.update(authenticate = "rejected")

# Add in this class to customized the Admin Interface
class ArtAdmin(ImportExportModelAdmin):
    list_display = ['id', 'identification', 'name', 'artist', 'category', 'type', 'agent', 'authenticate', ]
    search_fields = ('name', 'category', 'artist', 'id', 'authenticate', )

    actions = [approve_art, reject_art]
    list_filter = ["authenticate"]




class AgentAdmin(admin.ModelAdmin):
    list_display = ['id', 'name', 'phone', 'postcode', ]
    search_fields = ('name', 'id', )

class ArtResource(resources.ModelResource):

    class Meta:
        model = Art

# Update the registeration to include this customised interface
admin.site.register(Art, ArtAdmin)
admin.site.register(Agent, AgentAdmin)

You can customize the list of actions by overriding get_actions(). For example:

class ArtAdmin(ImportExportModelAdmin):
        list_display = ['id', 'identification', 'name', 'artist', 'category', 'type', 'agent', 'authenticate', ]
        search_fields = ('name', 'category', 'artist', 'id', 'authenticate', )
        list_filter = ["authenticate"]
        actions = [approve_art, reject_art]
   
        def get_actions(self, request):
            actions = super(ArtAdmin, self).get_actions(request)
            if not request.user.is_superuser:
               del actions[approve_art]
               del actions[reject_art]
            return actions

Check out https://docs.djangoproject.com/en/dev/ref/contrib/admin/actions/#conditionally-enabling-or-disabling-actions for more info