Custom asset transfer

The SDK provides the option to transfer assets within the same transaction, when making a contract call. By using add_custom_asset() you specify the asset ID, the amount, and the destination address:

        let amount = 1000;
        let _ = contract_instance
            .methods()
            .initialize_counter(42)
            .add_custom_asset(AssetId::zeroed(), amount, Some(some_addr.clone()))
            .call()
            .await?;