扩展RF，解决打印的日志信息中出现\xad\xfs\xff\xaa这样的字符

def _unic(item, *args):
    try:
        return unicode(item, *args)
    except UnicodeError:
        try:
            return str(item).decode("UTF-8")
        except UnicodeError:
            try:
                return str(item).decode("GBK")
            except UnicodeError:
                try:
                    ascii_text = str(item).encode(‘string_escape‘)
                except:
                    return _unrepresentable_object(item)
                else:
                    return unicode(ascii_text)
    except:
        return _unrepresentable_object(item)