code: function _readTemplateFile(fileName) {
      if (fileName) {
        try {
          fs.accessSync(fileName, fs.constants.R_OK);
          return fs.readFileSync(fileName, 'utf-8');
        } catch (err) {
          return fs.readFileSync(path.join(__dirname, '..', 'templates', fileName), 'utf-8');
        }
      } else {
        return "";
      }
    }
docs: Read a template file and return it's content
  @param {string} fileName
  @return {*} Content of the file
  @private