user: Question: Who played mixed doubles when Anna Keir played women's singles?
Columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1922', 'Arthur Evans Snell', 'C. A. Boone', 'P. C. G. Campbell H. L. Lafferty', 'C. A. Boone R. George', 'P. C. G. Campbell Mrs. P. C. G. Campbell']
SQL:

assistant: SELECT "Mixed doubles" FROM "Table" WHERE "Women's singles" = 'Anna Keir';