Assert\AssertionChain::nullOr PHP 메소드

Switch chain into mode allowing nulls, ignoring further assertions.

public nullOr ( ) : AssertionChain
리턴	AssertionChain

    public function nullOr()
    {
        if ($this->value === null) {
            $this->alwaysValid = true;
        }
        return $this;
    }

AssertionChain