fn topic_to_option<T>(topic: ethabi::Topic<T>) -> Option<Vec<T>> {
    match topic {
        ethabi::Topic::Any => None,
        ethabi::Topic::OneOf(v) => Some(v),
        ethabi::Topic::This(t) => Some(vec![t]),
    }
}
Converts a `Topic` to an equivalent `Option<Vec<T>>`, suitable for `FilterBuilder::topics`
core/lib/web3_decl/src/types.rs