code: func pieceStateRunStatusChars(psr PieceStateRun) (ret string) {
  	ret = fmt.Sprintf("%d", psr.Length)
  	ret += func() string {
  		switch psr.Priority {
  		case PiecePriorityNext:
  			return "N"
  		case PiecePriorityNormal:
  			return "."
  		case PiecePriorityReadahead:
  			return "R"
  		case PiecePriorityNow:
  			return "!"
  		case PiecePriorityHigh:
  			return "H"
  		default:
  			return ""
  		}
  	}()
  	if psr.Checking {
  		ret += "H"
  	}
  	if psr.Partial {
  		ret += "P"
  	}
  	if psr.Complete {
  		ret += "C"
  	}
  	if !psr.Ok {
  		ret += "?"
  	}
  	return
  }
docs: // Produces a small string representing a PieceStateRun.