src/ImportAbstract.php
public function startAt($startAt=0){
        if (!is_numeric($startAt) || $startAt < 0){
            throw new Exception("startAt: bad value", 10);
        }
        $this->startAt = $startAt;
        return $this;
    }
public function startAt($startAt=0){
        if (!is_numeric($startAt) || $startAt < 0){
            throw new Exception("startAt: bad value", 10);
        }
        $this->startAt = $startAt;
        return $this;
    }
Start at the line for Add

@param int $startAt

@return $this
@throws Exception