''' move to class kmanWindow kmanapp.py
        XXX
    def export_notes(self, bks, fnpref, ft='MD'):
        """format output and write to file
        markdown format:
        TYPE | bookname | author | marktime | content
        --|--|--|--|--
        xx|xx|xx|xx|xx

        CSV format:
        TYPE,bookname,author,marktime,content
        xx,xx,xx,xx,xx

        marktime: 20200403 PM 3:0:3 星期五
        
        Args:
            bks: books dict
            f: can be 'MD'/'JSON'/'CSV'

        Returns: special format of 'bks' dict
        """

        suff = {'MD':'.md','CSV':'.csv','JSON':'.json'}
        op = fnpref+suff[ft]

        with open(op, 'w', encoding='utf8', errors='ignore') as fw:
            if ft=='JSON':
                fw.write(json.dumps(bks, indent=4, sort_keys=True, ensure_ascii=False))
            elif ft in ['MD','CSV']:
                for s in self.format_note_data(bks, ft):
                    fw.write(s)
                    fw.write('\n')
            else:
                fw.write(json.dumps(bks)) # only for load back
    '''