-- Database schema
| cars : id [ INTEGER ] primary_key , train_id [ INTEGER ] cars.train_id = trains.id , position [ INTEGER ] , shape [ TEXT ] , len [ TEXT ] , sides [ TEXT ] , roof [ TEXT ] , wheels [ INTEGER ] , load_shape [ TEXT ] , load_num [ INTEGER ] | trains : id [ INTEGER ] primary_key , direction [ TEXT ] |
-- -- Please list the IDs of all the cars with double sides on trains that run in the west direction.

SELECT T1.id FROM cars AS T1 INNER JOIN trains AS T2 ON T1.train_id = T2.id WHERE T2.direction = 'east' AND T1.sides = 'double';