public function set_sortable_columns($columns)
    {
        if (! empty($this->sortable_columns)) {
            $columns = \array_merge($columns, $this->sortable_columns);
        }

        return $columns;
    }
public function set_sortable_columns($columns)
    {
        if (! empty($this->sortable_columns)) {
            $columns = \array_merge($columns, $this->sortable_columns);
        }

        return $columns;
    }
public function set_sortable_columns ( $ columns ) { if ( ! empty ( $ this -> sortable_columns ) ) { $ columns = \ array_merge ( $ columns , $ this -> sortable_columns ) ; } return $ columns ; }
Make custom columns sortable.

@since 1.0.0

@param array $columns Default WordPress sortable columns.
@return array
Make custom columns sortable .