user: Question: What is Incumbent, when District is "Louisiana 4"?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Results']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Louisiana 1', 'Bobby Jindal', 'Republican', 2004.0, 'Re-elected']
SQL:

assistant: SELECT "Incumbent" FROM "Table" WHERE "District" = 'Louisiana 4';