EXPLAIN CREATE TABLE AS

It turns out you cannot EXPLAIN on CREATE TABLE AS, but it seems to work
fine if I extend the grammar as below:

ExplainableStmt:
SelectStmt
| InsertStmt
| UpdateStmt
| DeleteStmt
| DeclareCursorStmt
+ | CreateAsStmt
| ExecuteStmt /* by default all are $$=$1 */
;

It's the same as SELECT INTO after all, which already works. Should
this be added?