code: function empty (args) {
      // make sure args is object
      args = requireValidOptionalObject(args)
      // to empty object data must be set to null
      args.data = null
      // use update method to empty
      return this.updateMeta(args)
  }
docs: @function empty
  
  empty object data
  
  @param {object} args
  
  @returns {Promise}