user: Question: Who directed the movie when John Wayne played the role of John Travers?
Columns: ['Title', 'Studio', 'Role', 'Leading lady', 'Director']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['The Lucky Texan', 'Mono', 'Jerry Mason', 'Barbara Sheldon', 'R.N. Bradbury']
SQL:

assistant: SELECT "Director" FROM "Table" WHERE "Role" = 'John Travers';