@Override public Value value(final QueryContext qc) throws QueryException { final FItem f = checkArity(exprs[1], 1, qc); final Iter iter = exprs[0].iter(qc); Item it = iter.next(); if (it == null) return Empty.SEQ; final Value v1 = f.invokeValue(qc, info, it); it = iter.next(); if (it == null) return v1; final ValueBuilder vb = new ValueBuilder().add(v1); do { vb.add(f.invokeValue(qc, info, it)); } while ((it = iter.next()) != null); return vb.value(); }