countAttr(xElem(_, A, Conts, _), AttrName) :- 
            hasKey(A, AttrName),
            1 + countContents(eFlat(Conts), AttrName)
            ;
countAttr(xElem(_, A, Conts, _), AttrName) :- 
            countContents(eFlat(Conts), AttrName)
            ;
countAttr(_, _) :- 0;

countContents(Enum, _) :- exhausted(Enum), 0
            ;
countContents(Enum, AttrName) :- 
            N = countAttr(eValue(Enum), AttrName),
            N + countContents(eNext(Enum), AttrName)
            ;

countElem(xElem(_, _, Conts, _)) :- 
            1 + countConts(eFlat(Conts))
            ;
countElem(_) :- 0;

countConts(Enum) :- exhausted(Enum), 0
            ;
countConts(Enum) :- 
            N = countElem(eValue(Enum)),
            N + countConts(eNext(Enum))
            ;

count(xDoc(Conts)) :- countConts(eFlat(Conts));
count(XML) :- countElem(XML);


replaceElem(xElem(Old, A, Conts, NS), Old, New) :- 
            xElem(New, A, replaceConts(eFlat(Conts), Old, New), NS)
            ;
replaceElem(xElem(Other, A, Conts, NS), Old, New) :- 
            xElem(Other, A, replaceConts(eFlat(Conts), Old, New), NS)
            ;
replaceElem(Other, _, _) :- Other;

replaceConts(Enum, Old, New) :- exhausted(Enum), []
            ;
replaceConts(Enum, Old, New) :- 
            Result = replaceElem(eValue(Enum), Old, New),
            [Result | replaceConts(eNext(Enum), Old, New)]
            ;










addElem(Tbl, xElem(Name, A, C, NS)) :- 
            (
                hasKey(Tbl, Name), 
                VectOfElems =  hGet(Tbl, Name),
                vAdd(VectOfElems, Name)
            ##
                hPut(Tbl, Name, newVector([xElem(Name, A, C, NS)]))
            );
addElem(Tbl, _) :- true;


xdoc() :- <a b="1"><c><a b="5"/>a</c></a>;