class Media

    def absolute_path(self, path):
        """
        Given a relative or absolute path to a static asset, return an absolute
        path. An absolute path will be returned unchanged while a relative path
        will be passed to django.templatetags.static.static().
        """
        if path.startswith(('http://', 'https://', '/')):
            return path
        return static(path)

    def add_css(self, data):
        if data:
            for medium, paths in data.items():
                for path in paths:
                    if not self._css.get(medium) or path not in self._css[medium]:
                        self._css.setdefault(medium, []).append(path)

    def add_js(self, data):
        if data:
            for path in data:
                if path not in self._js:
                    self._js.append(path)

    def render(self):
        return mark_safe('\n'.join(chain(*[getattr(self, 'render_' + name)() for name in MEDIA_TYPES])))

    def render_css(self):
        # To keep rendering order consistent, we can't just iterate over items().
        # We need to sort the keys, and iterate over the sorted list.
        media = sorted(self._css.keys())
        return chain(*[[
            format_html(
                '<link href="{}" type="text/css" media="{}" rel="stylesheet" />',
                self.absolute_path(path), medium
            ) for path in self._css[medium]
        ] for medium in media])

    def render_js(self):
        return [
            format_html(
                '<script type="text/javascript" src="{}"></script>',
                self.absolute_path(path)
            ) for path in self._js
        ]