Expression::Ptr CurrentFN::typeCheck(const StaticContext::Ptr &context,
                                     const SequenceType::Ptr &reqType)
{
    m_itemType = context->currentItemType();
    return FunctionCall::typeCheck(context, reqType);
}
Expression::Ptr CurrentFN::compress(const StaticContext::Ptr &context)
{
    m_itemType = context->currentItemType();
    return FunctionCall::compress(context);
}