user: Question: Who were the writers of episode 20?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [458.0, 1.0, '"Out of the Ashes"', 'Ian Gilmourn', 'Louise Crane-Bowes', '3February2009']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "No. in season" = 20.0;