array key: search
The search definition utilizes the standard search functionality used with List Tables. Simply defining the search array will cause the search box with query string variable name “s” to appear. The label will define the search button label and the id will define the text input id. The search terms must be accommodated via get_data and get_data_count for searching.
$list_table_definitions['search'] = array('label'=> "Search Make and Model", 'id' => "search_id");