user: Question: What is the maximum production code of the episode directed by Sean McNamara?
Columns: ['Series #', 'Season #', 'Title', 'Directed by', 'Written by', 'Original air date', 'Prod. code', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [22.0, 1.0, '"Out of Control"', 'Gerren Keith', 'Sarah Jane Cunningham & Suzie V. Freeman', 'October3,2003', 203.0, '2.9']
SQL:

assistant: SELECT MAX("Prod. code") FROM "Table" WHERE "Directed by" = 'Sean McNamara';