code: function files (directoryPath, options) {
    return readFiles(directoryPath, {
      glob: options && options.glob,
      stream: false,
      encoding: 'utf-8'
    })
  }
docs: An overridable directory which resolves to the contents of all its files (recursively).
  Returns an undefined value if the directory path is undefined.
  The contents of each file is a UTF-8 encoded string.
  @param {string|null|undefined} directoryPath the path to the directory
  @param {object=} options
  @param {string=} options.glob an optional glob pattern for filtering files
  @return {Promise<object<string,Promise<{path:string,contents:string}>>>} an object containing
  the relative file-path from the directoryPath as key and the file-path and the file-contents as value
  @deprecated Use {@link #readFiles} instead