code: func (schemas Schemas) TTLs() []uint32 {
  	ttls := make(map[uint32]struct{})
  	for _, s := range schemas.raw {
  		for _, r := range s.Retentions {
  			ttls[uint32(r.MaxRetention())] = struct{}{}
  		}
  	}
  	for _, r := range schemas.DefaultSchema.Retentions {
  		ttls[uint32(r.MaxRetention())] = struct{}{}
  	}
  	var ttlSlice []uint32
  	for ttl := range ttls {
  		ttlSlice = append(ttlSlice, ttl)
  	}
  	return ttlSlice
  }
docs: // TTLs returns a slice of all TTL's seen amongst all archives of all schemas