# File lib/sqlite3/driver/dl/driver.rb, line 267
      def progress_handler( db, n, data=nil, &block )
        @progress_handler = block

        unless @progress_handler_callback
          @progress_handler_callback = ::DL.callback( "IP" ) do |cookie|
            @progress_handler.call( cookie )
          end
        end

        API.sqlite3_progress_handler( db, n, block&&@progress_handler_callback,
          data )
      end