Devise\Users\Permissions\RuleManager::addRule PHP Method

    public function addRule($rule, $closure = null)
    {
        if ($this->ruleNameAvailable($rule)) {
            $this->RuleList->rules[] = $rule;
            $this->RuleList->closures[$rule] = $closure;
        } else {
            throw new \Devise\Support\DeviseException('Rule name "' . $rule . '" already in use.');
        }
    }