class_docstr: Import dashboard in JSON format.
  
  This is the original unversioned format used to export and import dashboards
  in Superset.
code: def run(self) -> None:
      self.validate()
  
      for file_name, content in self.contents.items():
          logger.info("Importing dashboard from file %s", file_name)
          import_dashboards(db.session, content, self.database_id)
  
imports: import json
  import logging
  import time
  from copy import copy
  from datetime import datetime
  from typing import Any, Optional
  from flask_babel import lazy_gettext
  from sqlalchemy.orm import make_transient, Session
  from superset import db
  from superset.commands.base import BaseCommand
  from superset.commands.dataset.importers.v0 import import_dataset
  from superset.connectors.sqla.models import SqlaTable, SqlMetric, TableColumn
  from superset.exceptions import DashboardImportException
  from superset.models.dashboard import Dashboard
  from superset.models.slice import Slice
  from superset.utils.dashboard_filter_scopes_converter import convert_filter_scopes, copy_filter_scopes
label_desc: Use image node_id 2 for calling the ImportDashboardsCommand obj's underlying member method code with example usage: obj.run() without return types