code: function config (args) {
      // make sure extension has .
      if (args && typeof args.ext === 'string' && args.ext.charAt(0) !== '.') {
          args.ext = '.'+args.ext
      }
      // merge config to global config
      mergeArgs(GLOBAL, args)
      // create regular expression for matching extension
      GLOBAL.extRegExp = new RegExp('\\'+GLOBAL.ext+'$')
      // return config
      return GLOBAL
  }
docs: @function config
  
  update/get config
  
  @param {object} args
  
  @returns {object}
  
  @throws {Error}