user: Question: Name the Visitor that has a Home of Chicago Black Hawks on April 20?
Columns: ['Date', 'Visitor', 'Score', 'Home', 'Record']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['April 13', 'Chicago Black Hawks', '1–4', 'Buffalo Sabres', '0-1']
SQL:

assistant: SELECT "Visitor" FROM "Table" WHERE "Home" = 'Chicago Black Hawks' AND "Date" = 'April 20';