old_contents: from accelerator.models import NavTree
  from accelerator.sitetree_navigation.utils import (
      add_user_roles_to_nav_items,
      create_items,
      delete_nav_tree,
      FLUENT_REDIRECT_URL,
      REGISTER_FOR_EVENTS_URL
  )
  from accelerator_abstract.models import BaseUserRole
  
  FINALIST = BaseUserRole.FINALIST
  ALUMNI = BaseUserRole.ALUM
  MENTOR = BaseUserRole.MENTOR
  STAFF = BaseUserRole.STAFF
  
  EVENTS_SUBNAV_TREE = {
      "title": 'Events Sub Nav',
      "alias": 'events_subnav'
  }
  
  EVENTS_SUBNAV_ITEMS = [
      {
          "title": 'Session Slides',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'event_session_slides',
      }, {
          "title": 'Calendar',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'event_calendar',
      }, {
          "title": 'Key Dates',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, MENTOR],
          "alias": 'event_key_dates',
      }, {
          "title": 'Register for Events',
          "url": REGISTER_FOR_EVENTS_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'register_for_events',
      }
  
  ]
  
  
  def create_events_subnav():
      tree, _ = NavTree.objects.update_or_create(
          alias=EVENTS_SUBNAV_TREE['alias'],
          defaults=EVENTS_SUBNAV_TREE)
      create_items(tree, EVENTS_SUBNAV_ITEMS)
      add_user_roles_to_nav_items(EVENTS_SUBNAV_ITEMS)
  
  
  def delete_events_subnav():
      delete_nav_tree(EVENTS_SUBNAV_TREE)
  
new_contents: from accelerator.models import NavTree
  from accelerator.sitetree_navigation.utils import (
      add_user_roles_to_nav_items,
      create_items,
      delete_nav_tree,
      FLUENT_REDIRECT_URL,
      REGISTER_FOR_EVENTS_URL
  )
  from accelerator_abstract.models import BaseUserRole
  
  FINALIST = BaseUserRole.FINALIST
  ALUMNI = BaseUserRole.ALUM
  MENTOR = BaseUserRole.MENTOR
  
  EVENTS_SUBNAV_TREE = {
      "title": 'Events Sub Nav',
      "alias": 'events_subnav'
  }
  
  EVENTS_SUBNAV_ITEMS = [
      {
          "title": 'Session Slides',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'event_session_slides',
      }, {
          "title": 'Calendar',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'event_calendar',
      }, {
          "title": 'Key Dates',
          "url": FLUENT_REDIRECT_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, MENTOR],
          "alias": 'event_key_dates',
      }, {
          "title": 'Register for Events',
          "url": REGISTER_FOR_EVENTS_URL,
          "urlaspattern": False,
          "display_single_item": False,
          'active_program': True,
          "user_roles": [FINALIST, ALUMNI, MENTOR],
          "alias": 'register_for_events',
      }
  
  ]
  
  
  def create_events_subnav():
      tree, _ = NavTree.objects.update_or_create(
          alias=EVENTS_SUBNAV_TREE['alias'],
          defaults=EVENTS_SUBNAV_TREE)
      create_items(tree, EVENTS_SUBNAV_ITEMS)
      add_user_roles_to_nav_items(EVENTS_SUBNAV_ITEMS)
  
  
  def delete_events_subnav():
      delete_nav_tree(EVENTS_SUBNAV_TREE)
  
subject: remove unnecessary imports