code: def main():
      
      print(main.__doc__)
      if '-h' in sys.argv:sys.exit() 
      cont,Int,Top=1,[],[]
      while cont==1:
          try: 
              Int.append(int(input(" Enter desired treatment step interval: <return> to quit ")))
              Top.append(int(input(" Enter upper bound for this interval: ")))
          except:
              cont=0
      pmag.chart_maker(Int,Top)
docs: Welcome to the thellier-thellier experiment automatic chart maker.   
      Please select desired step interval and upper bound for which it is valid.
      e.g.,   
      50 
      500
      10 
      600
      
      a blank entry signals the end of data entry.
      which would generate steps with 50 degree intervals up to 500, followed by 10 degree intervals up to 600.   
      
      chart is stored in:  chart.txt