code: func (s *State) SameLineage(other *State) bool {
  	s.Lock()
  	defer s.Unlock()
  
  	// If one of the states has no lineage then it is assumed to predate
  	// this concept, and so we'll accept it as belonging to any lineage
  	// so that a lineage string can be assigned to newer versions
  	// without breaking compatibility with older versions.
  	if s.Lineage == "" || other.Lineage == "" {
  		return true
  	}
  
  	return s.Lineage == other.Lineage
  }
docs: // SameLineage returns true only if the state given in argument belongs
  // to the same "lineage" of states as the receiver.