code: def stylus(input, output, **kw):
      
      stdin = open(input, 'r')
      stdout = open(output, 'w')
      cmd = '%s --include %s' % (current_app.config.get('STYLUS_BIN'),
                                 os.path.abspath(os.path.dirname(input)))
      subprocess.call(cmd, shell=True, stdin=stdin, stdout=stdout)
docs: Process Stylus (.styl) files