user: Question: How many different production codes does the episode directed by Dominic Polcino have?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [81.0, 1.0, '" Stewie Loves Lois "', 'Mike Kim', 'Mark Hentemann', 'September10,2006', '4ACX32']
SQL:

assistant: SELECT COUNT("Production code") FROM "Table" WHERE "Directed by" = 'Dominic Polcino';