code: func Tick(interval time.Duration, procfunc gp.ProcessFunc) gp.Process {
  	return gp.Go(func(proc gp.Process) {
  		ticker := time.NewTicker(interval)
  		callOnTicker(ticker.C, procfunc)(proc)
  		ticker.Stop()
  	})
  }
docs: // Tick constructs a ticker with interval, and calls the given ProcessFunc every
  // time the ticker fires.
  // This is sequentially rate limited, only one call will be in-flight at a time.
  //
  //  p := periodicproc.Tick(time.Second, func(proc goprocess.Process) {
  //  	fmt.Println("fire!")
  //  })
  //
  //  <-time.After(3 * time.Second)
  //  p.Close()
  //
  //  // Output:
  //  // fire!
  //  // fire!
  //  // fire!