Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Who directed the episode written by Dan Serafin and aired on July 23, 2008?

### Inputs:
table_name: table, columns: ['Prod. No.', 'Title', 'Written by', 'Directed by', 'Original airdate']

### Response:
SELECT Directed by FROM table WHERE Written by = dan serafin AND Original airdate = july 23, 2008