Improve example in doc for columns method
@@ -1148,7 +1148,7 @@ where
/// [[ 6, 7, 8], [ 9, 10, 11]]]);
///
/// // Here `columns` will yield the six generalized columns of the array.
- /// for row in a.columns() {
+ /// for column in a.columns() {
/// /* loop body */
/// }
/// ```
