user: Question: What entrant had a Maserati 250F chassis and fewer than 6 points before 1957?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1951.0, 'Scuderia Milano', 'Maserati 4CLT/48', 'Maserati Straight-4', 0.0]
SQL:

assistant: SELECT "Entrant" FROM "Table" WHERE "Chassis" = 'Maserati 250F' AND "Year" < 1957.0 AND "Points" < 6.0;