in migration.go [43:51]
func (m *Migrator) AddMigration(version uint, migration Migration) {
if len(m.migrations) > 0 && version <= m.migrations[len(m.migrations)-1].version {
panic("adding migration for a smaller version")
}
m.migrations = append(m.migrations, migrationEntry{
version: version,
migration: migration,
})
}