user: Question: Who was the leader at the summit earlier than 1956, when Carcassonne shows for finish?
Columns: ['Year', 'Stage', 'Start', 'Finish', 'Leader at the summit']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [2012.0, 17.0, 'Bagnères-de-Luchon', 'Peyragudes', 'Thomas Voeckler ( FRA )']
SQL:

assistant: SELECT "Leader at the summit" FROM "Table" WHERE "Year" < 1956.0 AND "Finish" = 'Carcassonne';