user: Question: What is the transfer fee of Diogo?
Columns: ['Name', 'Country', 'Status', 'Transfer window', 'Transfer fee']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Roberto Carlos', 'BRA', 'Contract Ended', 'Summer', 'Free']
SQL:

assistant: SELECT "Transfer fee" FROM "Table" WHERE "Name" = 'Diogo';