human
I wrote the below code

    def decorator(f):
        @wraps(f)
        def decorated(request, message_format, **kwargs):
            if (not settings.DEBUG):
                raise Http404
            if (message_format not in (u'text', u'html')):
                raise Http404
            result = f(request, **kwargs)
            if isinstance(result, HttpResponse):
                return result
            message = email_builder(**result)
            if (not message):
                raise Http404
            if (message_format == u'text'):
                content = message.body
                content_type = u'text/plain'
            else:
                for (content, content_type) in message.alternatives:
                    if (content_type == u'text/html'):
                        break
                else:
                    raise Http404
            content_type = (u'%s.
   charset=utf-8' % content_type)
            return HttpResponse(content, content_type=content_type)
        return decorated
    return decorator

What's a good function header?
 Here's a good function header?
assistant
#Here's a good function header.

def preview_email(email_builder):