user: Question: Thomas J. Lane is the incumbent of how many parties?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Massachusetts 1', 'John W. Heselton', 'Republican', 1944.0, 'Re-elected', 'John W. Heselton (R) 55.6% John J. Dwyer (D) 44.4%']
SQL:

assistant: SELECT COUNT("Party") FROM "Table" WHERE "Incumbent" = 'Thomas J. Lane';