text: numberList = list()
  while True:
      input = raw_input("Enter a number : ")
      if input == "done": break
  
      try :
          number = float(input)
          numberList.append(number)
      except :
          print 'Please enter only numbers. Instead of number you have entered -', input
  
  average = sum(numberList) / len(numberList)
  print "Average :", average
  