old_contents: from django.conf import settings
  from django.utils.importlib import import_module
  
  
  def get_module_and_model_names():
      s = (getattr(settings, "ARMSTRONG_SECTION_ITEM_MODEL", False) or
              "armstrong.apps.content.models.Content")
      return s.rsplit(".", 1)
  
  
  def get_item_model_class():
      module_name, class_name = get_module_and_model_names()
      module = import_module(module_name)
      return getattr(module, class_name)
  
  def filter_item_rels(rels):
      model_rels = []
      ItemModel = get_item_model_class()
      for related in rels:
          if issubclass(ItemModel, related.related_model):
              model_rels.append(related)
      return model_rels
  
  def get_section_relations(Section):
      """Find every relationship between section and the item model."""
      all_rels = [f for f in Section._meta.get_fields(include_hidden=True) if
                  f.is_relation and f.auto_created]
      return filter_item_rels(all_rels)
  
  def get_section_many_to_many_relations(Section):
      m2m_rels = [f for f in Section._meta.get_fields(include_hidden=True) if
                  f.many_to_many and f.auto_created]
      return filter_item_rels(m2m_rels)
  
new_contents: from django.conf import settings
  from django.utils.module_loading import import_module
  
  
  def get_module_and_model_names():
      s = (getattr(settings, "ARMSTRONG_SECTION_ITEM_MODEL", False) or
              "armstrong.apps.content.models.Content")
      return s.rsplit(".", 1)
  
  
  def get_item_model_class():
      module_name, class_name = get_module_and_model_names()
      module = import_module(module_name)
      return getattr(module, class_name)
  
  def filter_item_rels(rels):
      model_rels = []
      ItemModel = get_item_model_class()
      for related in rels:
          if issubclass(ItemModel, related.related_model):
              model_rels.append(related)
      return model_rels
  
  def get_section_relations(Section):
      """Find every relationship between section and the item model."""
      all_rels = [f for f in Section._meta.get_fields(include_hidden=True) if
                  f.is_relation and f.auto_created]
      return filter_item_rels(all_rels)
  
  def get_section_many_to_many_relations(Section):
      m2m_rels = [f for f in Section._meta.get_fields(include_hidden=True) if
                  f.many_to_many and f.auto_created]
      return filter_item_rels(m2m_rels)
  
subject: update import statement