code: def render_pdf(html, stylesheets=None,
                 download_filename=None, automatic_download=True):
      
      if not hasattr(html, 'write_pdf'):
          html = HTML(html)
      pdf = html.write_pdf(stylesheets=stylesheets)
      response = current_app.response_class(pdf, mimetype='application/pdf')
      if download_filename:
          if automatic_download:
              value = 'attachment'
          else:
              value = 'inline'
          response.headers.add('Content-Disposition', value,
                               filename=download_filename)
      return response
docs: Render a PDF to a response with the correct ``Content-Type`` header.
  
      :param html:
          Either a :class:`weasyprint.HTML` object or an URL to be passed
          to :func:`flask_weasyprint.HTML`. The latter case requires
          a request context.
      :param stylesheets:
          A list of user stylesheets, passed to
          :meth:`~weasyprint.HTML.write_pdf`
      :param download_filename:
          If provided, the ``Content-Disposition`` header is set so that most
          web browser will show the "Save as…" dialog with the value as the
          default filename.
      :param automatic_download:
          If True, the browser will automatic download file.
      :returns: a :class:`flask.Response` object.