lib/domain.js
function (fn) {
    if (!fn || !_.isFunction(fn) || fn.length !== 1) {
      var err = new Error('Please pass a valid function!');
      debug(err);
      throw err;
    }

    this.validatorExtension = fn;

    return this;
  }
function (fn) {
    if (!fn || !_.isFunction(fn) || fn.length !== 1) {
      var err = new Error('Please pass a valid function!');
      debug(err);
      throw err;
    }

    this.validatorExtension = fn;

    return this;
  }
function ( fn ) { if ( ! fn || ! _ . isFunction ( fn ) || fn . length !== 1 ) { var err = new Error ( 'Please pass a valid function!' ) ; debug ( err ) ; throw err ; } this . validatorExtension = fn ; return this ; }
Extends the validator instance.
@param   {Function} fn the function to be injected
@returns {Domain}      to be able to chain...
Extends the validator instance .