public function convert($item)
{
if ($this->header === null) {
$this->header = $item;
return $item;
}
$newItem = [];
foreach ($item as $key => $value) {
if (isset($this->header[$key])) {
$key = $this->header[$key];
}
$newItem[$key] = $value;
}
return $newItem;
}