code: func (m *Migrator) Migrations(status int) []*Migration {
  	// Sort all migration ids.
  	ids := make([]uint64, 0)
  	for id, _ := range m.migrations {
  		ids = append(ids, id)
  	}
  	sort.Sort(uint64slice(ids))
  
  	// Find ids for the given status.
  	migrations := make([]*Migration, 0)
  	for _, id := range ids {
  		migration := m.migrations[id]
  		if status == -1 || migration.Status == status {
  			migrations = append(migrations, migration)
  		}
  	}
  	return migrations
  }
docs: // Returns a sorted list of migration ids for a given status. -1 returns
  // all migrations.