user: Question: What is the entrant of a chassis Maserati 250F, also has 6 points and older than year 1957?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1952.0, 'Equipe Gordini', 'Gordini Type 16', 'Gordini Straight-6', '6']
SQL:

assistant: SELECT "Entrant" FROM "Table" WHERE "Chassis" = 'Maserati 250F' AND "Points" = '6' AND "Year" < 1957.0;