# L-14 MCS 260 12 Feb 2010 : histograms
#
# A voting machine tallies votes.
# We use two global variables in the main loop
# as arguments in a sequence.
#
tno = 0   # tno counts no votes
tyes = 0  # tyes counts yes votes

def poll():
   "asks whether approve or not"
   print 'Vote yes or no, 0 to stop'
   answer = raw_input('approve ? (y/n) ')
   return answer

def update(t,vote):
   "updates tally t with vote"
   if vote == 'y':
      return (t[0],t[1]+1)
   elif vote == 'n':
      return (t[0]+1,t[1])

while True:
   v = poll()
   if v == '0': break
   (tno,tyes) = update((tno,tyes),v)
print 'Tally of votes :', (tno,tyes)