code: func (isolators Isolators) assertValid() error {
  	typesMap := make(map[ACIdentifier]bool)
  	for _, i := range isolators {
  		v := i.Value()
  		if v == nil {
  			return ErrInvalidIsolator
  		}
  		if err := v.AssertValid(); err != nil {
  			return err
  		}
  		if _, ok := typesMap[i.Name]; ok {
  			if !v.multipleAllowed() {
  				return fmt.Errorf(`isolators set contains too many instances of type %s"`, i.Name)
  			}
  		}
  		for _, c := range v.Conflicts() {
  			if _, found := typesMap[c]; found {
  				return ErrIncompatibleIsolator
  			}
  		}
  		typesMap[i.Name] = true
  	}
  	return nil
  }
docs: // assertValid checks that every single isolator is valid and that
  // the whole set is well built