code: func NewMsgCFCheckpt(filterType FilterType, stopHash *chainhash.Hash,
  	headersCount int) *MsgCFCheckpt {
  	return &MsgCFCheckpt{
  		FilterType:    filterType,
  		StopHash:      *stopHash,
  		FilterHeaders: make([]*chainhash.Hash, 0, headersCount),
  	}
  }
docs: // NewMsgCFCheckpt returns a new bitcoin cfheaders message that conforms to
  // the Message interface. See MsgCFCheckpt for details.