code: func (mc MongoClient) ScrubAllValueDescriptors() error {
  	s := mc.getSessionCopy()
  	defer s.Close()
  
  	if _, err := s.DB(mc.database.Name).C(db.ValueDescriptorCollection).RemoveAll(nil); err != nil {
  		return errorMap(err)
  	}
  	return nil
  }
docs: // Delete all of the value descriptors