def __call__(request, result, encoding):
    """Return a modified result.

        `request` is the Zope request. Response headers may be read or
        modified in `request.response`.

        `result` is an iterable of byte strings that represents the response
        body. When unwound, its contents will match the response content type.

        `encoding` is the default encoding used.

        Return the new result iterable, or a string. If a string is returned,
        the Content-Type header will be updated automatically. If a six.text_type
        string is returned, it will be encoded with the current content
        encoding.

        Do not call `request.response.setBody()`. It will have no effect.
        """
