code: function _relativeCopy(fileGlob, from, to) {
    return glob(fileGlob, { cwd: from, nodir: true }, (err, files) => {
      if (err) throw err;
      files.forEach(file => {
        const origin = path.join(from, file);
        const dest = path.join(to, file);
        _recursiveMkDir(path.dirname(dest));
        fs.createReadStream(origin).pipe(fs.createWriteStream(dest));
      })
    })
  }
docs: Copy files maintaining relative paths.