Mystery Python code from G+

mystery_code.py

import random

list1 = ['a','b','c']
list2 = list1[:]

a_count = 0
b_count = 0
c_count = 0

def r_s():
    global a_count
    global b_count
    global c_count
    selected_letter = random.choice(list2)
    if selected_letter =='a':
        if a_count == 1:
            print "no a"
            list2.remove('a')
            return r_s()
        else:
            print selected_letter
            a_count += 1
            return r_s()
    elif selected_letter =='b':
        if b_count == 1:
            print "no b"
            list2.remove('b')
            return r_s()
        else:
            print selected_letter
            b_count +=1
            return r_s()
    elif selected_letter =='c':
        if c_count == 1:
            print "no c"
            list2.remove('c')
            return r_s()
        else:
            print selected_letter
            c_count += 1
            return r_s()
    else:
        print "no letters"

print r_s()