CREATE TABLE table_31055 ("Episode" FLOAT, "Airdate" TEXT, "Iron Chef" TEXT, "Challenger" TEXT, "Theme Ingredient" TEXT, "Winner" TEXT)

Who was the challenger when guillaume brahimi was the iron chef?
SELECT "Challenger" FROM table_31055 WHERE "Iron Chef" = 'Guillaume Brahimi'
SELECT "Challenger" FROM "table_31055" WHERE "Iron Chef" = 'Guillaume Brahimi'