user: Question: Who was the constructor of the car that went 56 laps and had a grid of 15?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Felipe Massa', 'Ferrari', '57', '1:31:06.970', '2']
SQL:

assistant: SELECT "Constructor" FROM "Table" WHERE "Laps" = '56' AND "Grid" = '15';