code: function moveModuleUp(source, target, module) {
    const targetZip = new JSZip();
  
    return fse
      .readFileAsync(source)
      .then(buffer => JSZip.loadAsync(buffer))
      .then(sourceZip => sourceZip.filter(file => file.startsWith(module + '/')))
      .map(srcZipObj =>
        zipFile(
          targetZip,
          srcZipObj.name.replace(module + '/', ''),
          srcZipObj.async('nodebuffer')
        )
      )
      .then(() => writeZip(targetZip, target));
  }
docs: Remove all modules but the selected module from a package.
  @param {string} source path to original package
  @param {string} target path to result package
  @param {string} module module to keep
  @return {Promise} the JSZip object written out.