def infectrate(R0, weeks, incoming, isprint=True):
     frontier = incoming # frontier is new, infectious cases by week   
     total = frontier        # total infections                                
     for week in range(1, weeks+1):                                            
             frontier = frontier * R0
             total += round(frontier)   # Python rounds .5 to nearest even
             if isprint:
                print("week,frontier,total", week,
                    # round(frontier,2), round(total-incoming,2))
                    round(frontier), round(total-incoming))
     return total-incoming