public function open()
{
	if ($this->publishable_type === 'credit') {
        // verify credit is available and anything else that
        // needs to be done before a credit job is opened
    } elseif ($this->publishable_type === 'daily) {
        // charge credit card or anything that needs to be
        // done before a daily job is opened
    } elseif ($this->publishable_type === 'plan' {
        // an elseif for any other types
    }

	$this->status = 'open';
    $this->save();
    // and any other code that has to be executed when a job is
    // opened regardless of which publishable type is chosen

	if ($this->publishable_type === 'credit') {
		// assign credit to job
	} elseif ($this->publishable_type === 'daily) {
		// whatever needs to be done for daily job
	} elseif ($this->publishable_type === 'plan' {
		// an elseif for any other types
	}
}