public function addValidationRule($rule, $expectation) {
		if ($rule && $expectation) {
			$this->validation_rules[$rule] = $expectation;
		}
		return $this;
	}
public function addValidationRule($rule, $expectation) {
		if ($rule && $expectation) {
			$this->validation_rules[$rule] = $expectation;
		}
		return $this;
	}
{@inheritdoc}