#pragma once
#include 
class ParentNode : public Node {
public:
    template void for_each_child(F) const;
    template void for_each_child(F);
protected:
    explicit ParentNode(Document& document, NodeType type)
        : Node(document, type)
    {
    }
};
template
inline void ParentNode::for_each_child(Callback callback) const
{
    for (auto* node = first_child(); node; node = node->next_sibling())
        callback(*node);
}
template
inline void ParentNode::for_each_child(Callback callback)
{
    for (auto* node = first_child(); node; node = node->next_sibling())
        callback(*node);
}