func checkPredRes(ret tree.Result, f *xpFilt, node tree.Node) (bool, error) {
if num, ok := ret.(tree.Num); ok {
if float64(f.proxPos[node.Pos()]) == float64(num) {
return true, nil
}
return false, nil
}
if b, ok := ret.(tree.IsBool); ok {
return bool(b.Bool()), nil
}
return false, fmt.Errorf("Cannot convert argument to boolean")
}
