code: func (pool *ReaderPool) noDups() bool {
  	seen := make(map[string]bool)
  	for info, _ := range pool.readerMap {
  		_, ok := seen[info.Info.Name]
  		assert(!ok)
  		seen[info.Info.Name] = true
  	}
  	return true
  }
docs: /* Make sure that every segment appears only once in the pool: */