function sammary() {
  const nodeFn = function ({ parentPaths, lang, item, isDir, result }) {
    const navTitle = generateNavTitle({ parentPaths, item, sign: isDir ? '-' : '*', lang });
    result.push(navTitle);
  };

  langs.forEach(dir => {
    const SUMMARY = 'SUMMARY.md';
    const targetFile = path.join(docsDir, `${dir}/${SUMMARY}`);

    const result = walk({
      catalog: docConfig.catalog,
      lang: dir,
      result: [],
      parentPaths: [],
      fn: nodeFn
    });

    if (result && result.length) {
      result.unshift('# whistle\n');
      fs.writeFileSync(targetFile, result.join('\n'));
    }
  });
}
function sammary() {
  const nodeFn = function ({ parentPaths, lang, item, isDir, result }) {
    const navTitle = generateNavTitle({ parentPaths, item, sign: isDir ? '-' : '*', lang });
    result.push(navTitle);
  };

  langs.forEach(dir => {
    const SUMMARY = 'SUMMARY.md';
    const targetFile = path.join(docsDir, `${dir}/${SUMMARY}`);

    const result = walk({
      catalog: docConfig.catalog,
      lang: dir,
      result: [],
      parentPaths: [],
      fn: nodeFn
    });

    if (result && result.length) {
      result.unshift('# whistle\n');
      fs.writeFileSync(targetFile, result.join('\n'));
    }
  });
}
function sammary ( ) { const nodeFn = function ( { parentPaths , lang , item , isDir , result } ) { const navTitle = generateNavTitle ( { parentPaths , item , sign : isDir ? '-' : '*' , lang } ) ; result . push ( navTitle ) ; } ; langs . forEach ( dir => { const SUMMARY = 'SUMMARY.md' ; const targetFile = path . join ( docsDir , ` ${ dir } ${ SUMMARY } ` ) ; const result = walk ( { catalog : docConfig . catalog , lang : dir , result : [ ] , parentPaths : [ ] , fn : nodeFn } ) ; if ( result && result . length ) { result . unshift ( '# whistle\n' ) ; fs . writeFileSync ( targetFile , result . join ( '\n' ) ) ; } } ) ; }
generate `SUMMARY.md` by `config.json`
generate SUMMARY . md by config . json