return this;
}
}
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
setStartExpression(visitor.optimize(start, contextItemType));
setStepExpression(step.optimize(visitor, start.getItemType(th)));
if (Literal.isEmptySequence(start) || Literal.isEmptySequence(step)) {