old_contents: from django.core import checks
  from django.utils.translation import ugettext_lazy as _
  
  from . import settings
  
  
  @checks.register("constance")
  def check_fieldsets(*args, **kwargs):
      """
      A Django system check to make sure that, if defined, CONFIG_FIELDSETS accounts for
      every entry in settings.CONFIG.
      """
      if hasattr(settings, "CONFIG_FIELDSETS") and settings.CONFIG_FIELDSETS:
          inconsistent_fieldnames = get_inconsistent_fieldnames()
          if inconsistent_fieldnames:
              return [
                  checks.Warning(
                      _(
                          "CONSTANCE_CONFIG_FIELDSETS is missing "
                          "field(s) that exists in CONSTANCE_CONFIG."
                      ),
                      hint=", ".join(sorted(inconsistent_fieldnames)),
                      obj="settings.CONSTANCE_CONFIG",
                      id="constance.E001",
                  )
              ]
      return []
  
  
  def get_inconsistent_fieldnames():
      """
      Returns a set of keys from settings.CONFIG that are not accounted for in
      settings.CONFIG_FIELDSETS.
      If there are no fieldnames in settings.CONFIG_FIELDSETS, returns an empty set.
      """
      field_name_list = []
      for fieldset_title, fields_list in settings.CONFIG_FIELDSETS.items():
          for field_name in fields_list:
              field_name_list.append(field_name)
      if not field_name_list:
          return {}
      return set(set(settings.CONFIG.keys()) - set(field_name_list))
  
new_contents: from django.core import checks
  from django.utils.translation import ugettext_lazy as _
  
  
  
  @checks.register("constance")
  def check_fieldsets(*args, **kwargs):
      """
      A Django system check to make sure that, if defined, CONFIG_FIELDSETS accounts for
      every entry in settings.CONFIG.
      """
      from . import settings
  
      if hasattr(settings, "CONFIG_FIELDSETS") and settings.CONFIG_FIELDSETS:
          inconsistent_fieldnames = get_inconsistent_fieldnames()
          if inconsistent_fieldnames:
              return [
                  checks.Warning(
                      _(
                          "CONSTANCE_CONFIG_FIELDSETS is missing "
                          "field(s) that exists in CONSTANCE_CONFIG."
                      ),
                      hint=", ".join(sorted(inconsistent_fieldnames)),
                      obj="settings.CONSTANCE_CONFIG",
                      id="constance.E001",
                  )
              ]
      return []
  
  
  def get_inconsistent_fieldnames():
      """
      Returns a set of keys from settings.CONFIG that are not accounted for in
      settings.CONFIG_FIELDSETS.
      If there are no fieldnames in settings.CONFIG_FIELDSETS, returns an empty set.
      """
      from . import settings
  
      field_name_list = []
      for fieldset_title, fields_list in settings.CONFIG_FIELDSETS.items():
          for field_name in fields_list:
              field_name_list.append(field_name)
      if not field_name_list:
          return {}
      return set(set(settings.CONFIG.keys()) - set(field_name_list))
  
subject: Fix #410 (#412)