docs: def import_field(field_classpath):
      """
      Imports a field by its dotted class path, prepending "django.db.models"
      to raw class names and raising an exception if the import fails.
      """
      if '.' in field_classpath:
          fully_qualified = field_classpath
      else:
          fully_qualified = "django.db.models.%s" % field_classpath
      try:
          return import_dotted_path(fully_qualified)
      except ImportError:
          raise ImproperlyConfigured("The EXTRA_MODEL_FIELDS setting contains "
                                     "the field '%s' which could not be "
                                     "imported." % field_classpath)