user: Question: How many parties does William B. Cravens represent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Arkansas 1', 'William J. Driver', 'Democratic', 1920.0, 'Lost renomination Democratic hold', 'Ezekiel C. Gathings (D) Unopposed']
SQL:

assistant: SELECT COUNT("Party") FROM "Table" WHERE "Incumbent" = 'William B. Cravens';