Even after #1576, we still have to reconcile the fact that domains were designed to be a set of identifiers for different learning contexts, while network is intended to be an identifier for a single "smart contracts" context.

This problem is specially problematic for StakeHolder as its configuration inherits from CharacterConfiguration, which has domains, but StakeHolder should have a single network instead.

As a consequence, we end up with weird mappings like:
network=list(self.domains)[0] (see e.g., nucypher/config/node.py after #1576)
or the other way around:
domains={self.network} (see e.g., nucypher/cli/commands/stake.py after #1576)