user: Question: what is the sum of laps when grid is less than 20 and Johnny Herbert is driving?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Johnny Herbert', 'Stewart - Ford', 66.0, '1:41:54.314', 14.0]
SQL:

assistant: SELECT SUM("Laps") FROM "Table" WHERE "Grid" < 20.0 AND "Driver" = 'Johnny Herbert';