user: Question: Name the successor for Pennsylvania 15th
Columns: ['District', 'Vacator', 'Reason for change', 'Successor', 'Date successor seated']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Oklahoma 7th', 'Sam C. Massingale (D)', 'Died January 17, 1941', 'Victor Wickersham (D)', 'April 1, 1941']
SQL:

assistant: SELECT "Successor" FROM "Table" WHERE "District" = 'Pennsylvania 15th';