public override void Walk(PythonWalker walker) {
if (walker.Walk(this)) {
if (_key != null) {
_key.Walk(walker);
}
if (_value != null) {
_value.Walk(walker);
}
if (_iterators != null) {
foreach (ComprehensionIterator ci in _iterators) {
ci.Walk(walker);
}
}
}
walker.PostWalk(this);
}