code: def pre_add(self, item: "DashboardModelView") -> None:
      item.slug = item.slug or None
      if item.slug:
          item.slug = item.slug.strip()
          item.slug = item.slug.replace(" ", "-")
          item.slug = re.sub(r"[^\w\-]+", "", item.slug)
      if g.user not in item.owners:
          item.owners.append(g.user)
      utils.validate_json(item.json_metadata)
      utils.validate_json(item.position_json)
      for slc in item.slices:
          slc.owners = list(set(item.owners) | set(slc.owners))
  
imports: import builtins
  import json
  import re
  from typing import Callable, Union
  from flask import g, redirect, request, Response
  from flask_appbuilder import expose
  from flask_appbuilder.actions import action
  from flask_appbuilder.models.sqla.interface import SQLAInterface
  from flask_appbuilder.security.decorators import has_access
  from flask_babel import gettext, lazy_gettext
  from flask_login import AnonymousUserMixin, login_user
  from superset import db, event_logger, is_feature_enabled, security_manager
  from superset.constants import MODEL_VIEW_RW_METHOD_PERMISSION_MAP, RouteMethod
  from superset.models.dashboard import Dashboard
  from superset.superset_typing import FlaskResponse
  from superset.utils import core
  from superset.views.base import BaseSupersetView, common_bootstrap_payload, DeleteMixin, generate_download_headers, SupersetModelView
  from superset.views.dashboard.mixin import DashboardMixin
label_desc: Use image node_id 4 for calling the DashboardModelView obj's underlying member method code with example usage: obj.pre_add(item) without return types