# L-14 MCS 260 Fri 12 Feb 2010 : histograms
#
# A voting machine tallies votes.
# In this second version we use a list to
# tally votes and use call by reference
# in this way.
#
tally = [0,0] # tally[0] counts no votes
              # tally[1] 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':
      t[1] += 1
   elif vote == 'n':
      t[0] += 1

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