public function sortable($sortable)
    {
        foreach ($sortable as $column => $options) {
            $this->sortable[$column] = $options;
        }

        return $this;
    }
public function sortable($sortable)
    {
        foreach ($sortable as $column => $options) {
            $this->sortable[$column] = $options;
        }

        return $this;
    }
public function sortable ( $ sortable ) { foreach ( $ sortable as $ column => $ options ) { $ this -> sortable [ $ column ] = $ options ; } return $ this ; }
Set columns that are sortable
@param  string  $column     the slug of the column
@param  string  $meta_value the meta_value to orderby
@param  boolean $is_num     whether to order by string/number
Set columns that are sortable