code/ViewableWrapper.php
public function isLiveVar($fieldName)
    {
        return $this->liveVars && (!is_array($this->liveVars) || in_array($fieldName, $this->liveVars));
    }
public function isLiveVar($fieldName)
    {
        return $this->liveVars && (!is_array($this->liveVars) || in_array($fieldName, $this->liveVars));
    }
Is this variable live in published mode?
@param string $field
@return bool