val migrations = listOf<() -> Unit>(
    { /* migration function code, or reference thereto */ }, // migration 1
    { /* migration function code, or reference thereto */ }, // migration 2
    { /* migration function code, or reference thereto */ }, // migration 3
    { /* migration function code, or reference thereto */ }, // migration 4
)

object Migrations : Table("migrations") {
    val latestRunMigration = integer("latest_run_migration")
    override val primaryKey: PrimaryKey = PrimaryKey(latestRunMigration)
}

val totalMigrations = migrations.size // list from above

// this function is called on startup, after the database is connected, but before the webserver handles connections (in `init = {` at ServiceInitialization)
fun runNeededMigrations() {
    val lastRunMigration = getLatestRunMigration() // select on Migration table
    if (totalMigrations > lastRunMigration) {
        // additional migrations have to run
        migrations.drop(latestMigration).forEachIndexed { index, migration -> // only run migrations that have not yet been run
            // next migration
            migration.invoke()
            setLastestRunMigration(lastRunMigration + index + 1)
        }
    }
}