public function isNullable()
    {
        if (is_null($this->nullable)) {
            $this->nullable = $this->isRuleExists('nullable');
        }

        return $this->nullable;
    }
public function isNullable()
    {
        if (is_null($this->nullable)) {
            $this->nullable = $this->isRuleExists('nullable');
        }

        return $this->nullable;
    }
public function isNullable ( ) { if ( is_null ( $ this -> nullable ) ) { $ this -> nullable = $ this -> isRuleExists ( 'nullable' ) ; } return $ this -> nullable ; }
Checks if the rules is nullable

@return bool
Checks if the rules is nullable