code: public function insert( $data, $format = null ) {
  		global $wpdb;
  
  		$wpdb->insert( $this->table, $data, $format );
  
  		return $wpdb->insert_id;
  	}
docs: Insert a row into a table
  
  @see wpdb::insert()
  
  @param array $data   Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
  @param array $format (Optional) An array of formats to be mapped to each of the value in $data.
  
  @return mixed