code: function handleGlob(glob) {
  	if (glob === '-') {
  		return stdinCache.then(stdin => [{content: stdin}]);
  	}
  	return globby(glob.split(' '), {nodir: true}).then(files => Promise.all(files.map(handleFile)));
  }
docs: FileToConcat describe the filename, content and sourcemap to concatenate.
  
  @typedef {Object} FileToConcat
  @property {String} file
  @property {String} content
  @property {Object} sourcemap
   
  Retrieve files matched by the gloc and call {@link handleFile} for each one found.
  If the glob is '-' return one FileToConcat with stdin as its content.
  
  @param  {String} glob the glob expression for which to retrive files.
  @return {Promise<FileToConcat[]>} a Promise that resolve to an Array of FileToConcat.