code: func (f *File) SetPriority(prio piecePriority) {
  	f.t.cl.lock()
  	defer f.t.cl.unlock()
  	if prio == f.prio {
  		return
  	}
  	f.prio = prio
  	f.t.updatePiecePriorities(f.firstPieceIndex(), f.endPieceIndex())
  }
docs: // Sets the minimum priority for pieces in the File.