user: Question: What is the total number of seats with gavin duffy in series 4?
Columns: ['Seat', 'Series 1', 'Series 3', 'Series 4', 'Series 5']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, "Niall O'Farrell", "Niall O'Farrell", "Niall O'Farrell", 'Peter Casey (businessman)']
SQL:

assistant: SELECT COUNT("Seat") FROM "Table" WHERE "Series 4" = 'gavin duffy';