public function columns($columns = [])
{
if (func_num_args() == 0) {
return $this->columns;
}
if (func_num_args() == 1 && is_array($columns)) {
foreach ($columns as $column => $label) {
$this->column($column, $label);
}
return;
}
foreach (func_get_args() as $column) {
$this->column($column);
}
}