The second version of a minimal user-upgradeable ledger. This version is not designed to be upgraded further — it lacks InitiateMigration and MigrateMyTokens entrypoints. However, it has MigrateFrom (callable from V1), and mints new tokens when a user calls V1.MigrateMyTokens. Other functions (either upgradeability-related or standard Transfer/GetTotalSupply may be added if deemed desirable).

Note that the naming in this module is different from Lorentz.Contracts.Upgradeable: by "migration" here we mean the process of transferring the value from an old contract to the new one rather than applying a transformation to storage. Thus, MigrationScript here is a lambda that forges an operation to migrate user's funds rather than a function that upgrades storage in-place.