user: Question: Who is the vacator for the February 1, 1971 date of successor's formal installation?
Columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', "Date of successor's formal installation"]
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Georgia (2)', 'Richard Russell, Jr. (D)', 'Died January 21, 1971', 'David H. Gambrell (D)', 'February 1, 1971']
SQL:

assistant: SELECT "Vacator" FROM "Table" WHERE "Date of successor's formal installation" = 'February 1, 1971';