user: Question: what is the class when the quantity is 4?
Columns: ['Class', 'Railway number(s)', 'Quantity', 'Year(s) of manufacture', 'Axle arrangement ( UIC )']
Types: ['text', 'text', 'real', 'text', 'text']
Sample row: ['None', 'I–II', 2.0, '1898', 'Bo′2′ g2t']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "Quantity" = 4.0;