user: Question: Who was the visitor on December 15, 1976?
Columns: ['Date', 'Visitor', 'Score', 'Home', 'Record']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['December 2, 1976', 'San Antonio Spurs', '116-124', 'Golden State Warriors', '11-10']
SQL:

assistant: SELECT "Visitor" FROM "Table" WHERE "Date" = 'December 15, 1976';