Implements an interface and "return"

I was implement an interface about Element, I had declear all of the methods of ELement and its superclass Node. Then it ask for return statement for everymethod.
actually, I only need some of the method, so what can I return for the empty method body. and for the methods I wanted, even I dont have any further programming for those methods, like "boolean hasAttrubute(String value), it still remian as an empty methods, what can I return for those?

Like I said before if some of the methods do not apply
in the subclass, you still have to provide meaningful
implementations for them. The proper thing to do is to
throw an UnsupportedOperationException.If this is an implementation of the DOM Element, doing that will get you nowhere fast.

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