code: function copyFile(src, dist) {
      return new Promise((resolve, reject) => {
          let rs = fs.createReadStream(path.cwd(src)),
              ws = fs.createWriteStream(path.cwd(dist));
  
          // 监听事件
          rs.on('error', reject);
          ws.on('error', reject);
          ws.on('close', resolve);
  
          // 传输文件
          rs.pipe(ws);
      });
  }
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