pub fn overrides_handle<B: BlockT<Hash = H256>, C, BE>(
    client: Arc<C>
) -> Arc<OverrideHandle<B>>
where C: ProvideRuntimeApi<B> + StorageProvider<B, BE> + AuxStore + HeaderBackend<B> + HeaderMetadata<B, Error = Error> + Send + Sync + 'static, C::Api: ApiExt<B> + EthereumRuntimeRPCApi<B> + ConvertTransactionRuntimeApi<B>, BE: Backend<B> + 'static, BE::State: StateBackend<BlakeTwo256>,