c# - GetEnumerator returns null -

object htmldocument.body.all not null. why getenumerator() return null?

ienumerator<htmlelement> hm =  htmldocument.body.all.getenumerator()       ienumerator<htmlelement>;

i think want this. although why want enumerator<htmlelement> have no clue.

ienumerator<htmlelement> hm =  htmldocument.body.all                .oftype<htmlelement>()                .getenumerator();

in cases find can things more with

foreach(var element in htmldocument.body.all.oftype<htmlelement>()) {      //stuff }

And