user: Question: Who wrote the last episode (episode 15) of season 3?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [45.0, 1.0, '"The Magnificent Seven"', 'Kim Manners', 'Eric Kripke', 'October4,2007', '3T6901', '2.97']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "No. in season" = 15.0;