docs: def html_to_pdf(content, encoding="utf-8",
                  link_callback=fetch_resources, **kwargs):
      """
      Converts html ``content`` into PDF document.
  
      :param unicode content: html content
      :returns: PDF content
      :rtype: :class:`bytes`
      :raises: :exc:`~easy_pdf.exceptions.PDFRenderingError`
      """
      src = BytesIO(content.encode(encoding))
      dest = BytesIO()
  
      pdf = pisa.pisaDocument(src, dest, encoding=encoding,
                              link_callback=link_callback, **kwargs)
      if pdf.err:
          logger.error("Error rendering PDF document")
          for entry in pdf.log:
              if entry[0] == xhtml2pdf.default.PML_ERROR:
                  logger_x2p.error("line %s, msg: %s, fragment: %s", entry[1], entry[2], entry[3])
          raise PDFRenderingError("Errors rendering PDF", content=content, log=pdf.log)
  
      if pdf.warn:
          for entry in pdf.log:
              if entry[0] == xhtml2pdf.default.PML_WARNING:
                  logger_x2p.warning("line %s, msg: %s, fragment: %s", entry[1], entry[2], entry[3])
  
      return dest.getvalue()