user: Question: What was the constructor for Jo Bonnier of 6 rounds?
Columns: ['Entrant', 'Constructor', 'Chassis', 'Engine', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Scuderia Sud Americana', 'Maserati', '250F', 'Maserati 250F1 2.5 L6', 'Juan Manuel Fangio', '1']
SQL:

assistant: SELECT "Constructor" FROM "Table" WHERE "Entrant" = 'Jo Bonnier' AND "Rounds" = '6';