'Remove granular permission perm from user on an object instance'

def delete_user_permissions(self, user, perm, obj, check_groups=False):

    user_perms = self.user_permissions(user, perm, obj, check_groups=False)
    if (not user_perms.filter(object_id=obj.id)):
        return
    perms = self.user_permissions(user, perm, obj).filter(object_id=obj.id)
    perms.delete()
