| 123456789101112131415161718192021222324252627 | package coreimport (  "fmt")type VPoint struct {  config VConfig  connHandler ConnectionHandler}func NewVPoint(config *VConfig) (*VPoint, error) {  var vpoint *VPoint  return vpoint, nil}type ConnectionHandler interface {  Listen(port uint16) error}func (vp *VPoint) Start() error {  if vp.config.Port <= 0 {    return fmt.Errorf("Invalid port %d", vp.config.Port)  }  vp.connHandler.Listen(vp.config.Port)  return nil}
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