src/import.js
async function filesInDirectories(dirPaths, options) {
  let files = await Promise.all(makeArray(dirPaths).map(dirPath=>_filesInDirectory(dirPath, options)));
  return flattenDeep(files);
}
async function filesInDirectories(dirPaths, options) {
  let files = await Promise.all(makeArray(dirPaths).map(dirPath=>_filesInDirectory(dirPath, options)));
  return flattenDeep(files);
}
async function filesInDirectories ( dirPaths , options ) { let files = await Promise . all ( makeArray ( dirPaths ) . map ( dirPath => _filesInDirectory ( dirPath , options ) ) ) ; return flattenDeep ( files ) ; }
Get all the files in a collection of directories.

@param {Array|Set|string} dirPaths     Path(s) to get files from.
@param [options]                       Import options object.
Get all the files in a collection of directories .