Voluptuous required and optional question

I want to modify a component to accept an other type of input (IOTA component : https://github.com/home-assistant/home-assistant/blob/dev/homeassistant/components/iota.py)

The idea would be to accept either a seed OR an address. But I do not know if it is possible or how to code it. The idea is that I do not want to put my seed (private key) in home-assistant configuration, so I would prefer to monitor a specific address (public key). The code is quite simple and would only need minor adjustments, but to do it, it would need to accept either a seed or an address.