public function setEffectType($effectType)
	{
		$available = [self::FADE_IN, self::FADE_OUT];
		
		if ( ! is_scalar($effectType) || ! in_array($effectType, $available, false))
		{
			throw new \InvalidArgumentException(sprintf('Wrong effect type value for %s, available values are %s',
				(string) $effectType, implode(', ', $available)));
		}
		
		$this->effectType = (string) $effectType;
		
		return $this;
	}