code: func (m *Manager) UpsertRegisteringUser(ipr *InProgressRegistration) error {
  	selector := bson.M{"sessionkey": ipr.SessionKey}
  	_, err := m.collection.Upsert(selector, ipr)
  	return err
  }
docs: // UpsertRegisteringUser creates a new or updates an existing entry in the db for a user currenly registering