user: Question: What is the total diagram for builder York?
Columns: ['Lot No.', 'Diagram', 'Built', 'Builder', 'Fleet numbers']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [30485.0, 97.0, '1957–1958', 'York', '1801–1812']
SQL:

assistant: SELECT SUM("Diagram") FROM "Table" WHERE "Builder" = 'York';