PHPML\Exception\InvalidArgumentException::invalidLayersNumber PHP 메소드

    public static function invalidLayersNumber()
    {
        return new self('Provide at least 2 layers: 1 input and 1 output');
    }

 /**
  * @param array                   $layers
  * @param ActivationFunction|null $activationFunction
  *
  * @throws InvalidArgumentException
  */
 public function __construct(array $layers, ActivationFunction $activationFunction = null)
 {
     if (count($layers) < 2) {
         throw InvalidArgumentException::invalidLayersNumber();
     }
     $this->addInputLayer(array_shift($layers));
     $this->addNeuronLayers($layers, $activationFunction);
     $this->addBiasNodes();
     $this->generateSynapses();
 }