code: function defaultUuid(options, version) {
    if (options && options.default) {
      if ([version, 'empty'].indexOf(options.default) > -1) {
        return options.default;
      }
      return version;
    }
    return undef;
  }
docs: Ensure that `uuid` type joi objects have a default specified.
  
  @param {DefaultSpecifierOptions} [options] - possible default options
  @property {String} options.default - [empty, v1, v4]
  @param {String} version - the uuid version that should be used as a default if no other default is specified
  @returns {(Undefined|String)} - the value that will identify the appropriate default to the default handler on the validator