user: Question: What is the number of production codes for episode #73?
Columns: ['Episode #', 'Season Episode #', 'Title', 'Directed by', 'Written by', 'Original air date', 'Prod. code']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['66', '1', '"Ill Suited"', 'Steve Loter', 'Brian Swenlin', 'February10,2007', '401']
SQL:

assistant: SELECT COUNT("Prod. code") FROM "Table" WHERE "Episode #" = '73';