protected function processReference($value)
    {
        if ($this->isReference($value)) {
            
            list($class, $identifier) = $this->processTypedIdentifier($value);
            
            if (!$this->getFactory()->hasFixture($class, $identifier)) {
                
                throw new InvalidArgumentException(
                    sprintf(
                        'No fixture definition found for %s.%s',
                        $class,
                        $identifier
                    )
                );
                
            }
            
            return $this->getFactory()->getFixture($class, $identifier);
        }
    }