Depending on settings calls either `format_keys` or `format_field_names`

def _format_object(obj, format_type=None):
    """Depending on settings calls either `format_keys` or `format_field_names`"""

    if json_api_settings.FORMAT_KEYS is not None:
        return format_keys(obj, format_type)

    return format_field_names(obj, format_type)