user: Question: Who wrote the episode with production code 2J5568?
Columns: ['No.', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '" A World Full of Strangers "', 'Allan Arkush', 'Kevin Murphy', 'September8,2010', '2J5591', '3.02']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Production code" = '2J5568';