#!/usr/bin/python
from itertools import *


#for i in count(10,2):
#    if i > 20:
#        break
#    else: 
 #       print "hey {}".format(i)

l = 'ATGCATGx'
list = []
for i in islice(l,0,len(l)+1, 2):
    list.append(i)

print list
    
    
