user: Question: Who directed the episode written by Dan Serafin and aired on July 23, 2008?
Columns: ['Prod. No.', 'Title', 'Written by', 'Directed by', 'Original airdate']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1', '"The Good, the Bad and the Snotty"', 'Jed Spingarn', 'T.J. Sullivan & Mike Gasaway', 'September 29, 2007']
SQL:

assistant: SELECT "Directed by" FROM "Table" WHERE "Written by" = 'Dan Serafin' AND "Original airdate" = 'July 23, 2008';