user: Question: Who was the writer of the episode number in series 4?
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original airdate', 'Production code']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1–2', '"Ben 10 Returns"', 'Dan Riba and Butch Lukic', 'Dwayne McDuffie', 'April18,2008', '101–102']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "No. in series" = '4';