Table:
driver	constructor	laps	time / retired	grid

alain prost	mclaren - tag	67	1:35:13.284	2

michele alboreto	ferrari	67	+ 23.911	5

nelson piquet	brabham - bmw	67	+ 24.922	1

niki lauda	mclaren - tag	67	+ 43.086	15

rené arnoux	ferrari	67	+ 1:01.430	6

riccardo patrese	alfa romeo	66	+ 1 lap	9

andrea de cesaris	ligier - renault	65	+ 2 laps	17

mauro baldi	spirit - hart	65	+ 2 laps	24

thierry boutsen	arrows - bmw	64	ignition	11

françois hesnault	ligier - renault	64	+ 3 laps	19

derek warwick	renault	61	overheating	7

jo gartner	osella - alfa romeo	60	fuel system	22

teo fabi	brabham - bmw	57	gearbox	10

nigel mansell	lotus - renault	51	engine	8

patrick tambay	renault	47	fuel system	3

eddie cheever	alfa romeo	37	fuel system	13

philippe alliot	ram - hart	37	turbo	25

jonathan palmer	ram - hart	35	turbo	21

jacques laffite	williams - honda	27	engine	14

elio de angelis	lotus - renault	25	turbo	23

stefan johansson	toleman - hart	17	overheating	26

keke rosberg	williams - honda	0	collision	4

ayrton senna	toleman - hart	0	collision	12

marc surer	arrows - bmw	0	collision	16

gerhard berger	ats - bmw	0	collision	18

piercarlo ghinzani	osella - alfa romeo	0	collision	20

At row 21 and column 4 of this table, retrieve and report the content of the corresponding cell. Output the target cell content as JSON in the format {"row_id":"m", "column_id":"n", "cell_value":"<Corresponding Cell Value>"}.

The target cell value in row 21 and column 4 is {"row_id":"21", "column_id":"4", "cell_value":"turbo"}.