+ // Find the previous move.
+ var previous_move_num, previous_toplay;
+ if (data['position']['toplay'] == 'B') {
+ previous_move_num = data['position']['move_num'];
+ previous_toplay = 'W';
+ } else {
+ previous_move_num = data['position']['move_num'] - 1;
+ previous_toplay = 'B';
+ }
+