Model:
facts+=Fact*;

Fact:
	Enumerat|Pred
;

Enumerat:
name=ID'+' (':=' '{' elements+=EnmElm (',' elements+=EnmElm)* '}')?;

EnmElm:
name=ID;

Pred: 
'Is' test=[Enumerat] '==' elem=[EnmElm] '?';

Enum+ := {one,two}

Is Enum == one ?

    override getScope(EObject context, EReference reference) {
        // We want to define the Scope for the Element's superElement cross-reference
        if (context instanceof Pred
                && reference == MyDslPackage.Literals.PRED__ELEM) {
            // ask the pred from its test and the test for its elements
            val candidates = (context as Pred).test.elements
            return Scopes.scopeFor(candidates)
        }
        return super.getScope(context, reference);
    }