code: function build(validatorName, validatorOptions) {
  
      if (typeof validatorBuildersRepository[validatorName] !== 'function') {
          throw validatorName + ' does not exists. use addValidatorBuilder to add a new validation rule';
      }
  
      return validatorBuildersRepository[validatorName](ValidationState, stateEnum, validatorOptions);
  }
docs: Adds validator builder. Use to create custom validation rules.
  @memberof! vivalid.validatorRepo
  @function
  @private
  @param {validatorName} name validator name.
  @param {object} validatorOptions.