docs: function prepare_babelrc() {
      debug('Parse: prepare babelrc');
      var filename = path.join(__dirname, '../babelrc/babelrc_v' + version());
      debug('Parse: use ' + filename);
      var to = path.join(bwd, '.babelrc');
      var content = prepare_babelrc_content(filename);
      fs.writeFileSync(to, JSON.stringify(content, null, 4));
      //cp.execSync('cp ' + filename + ' ' + path.join(bwd, '.babelrc'));
      process.on('exit', function (code) {
          debug('Parse: clear .babelrc ' + to);
          cp.execSync('rm -f ' + to);
      });
  }