import itertools
natuals=itertools.count(1)
ns=itertools.takewhile(lambda x:x <=10,natuals)
print(ns)
for c in itertools.chain('ABC','XYZ'):
print(c)
for key,group in itertools.groupby('AAABBBCCCC'):
print(key,list(group))
# your code goes here
# your code goes here
aW1wb3J0IGl0ZXJ0b29scwpuYXR1YWxzPWl0ZXJ0b29scy5jb3VudCgxKQpucz1pdGVydG9vbHMudGFrZXdoaWxlKGxhbWJkYSB4OnggPD0xMCxuYXR1YWxzKQpwcmludChucykKZm9yIGMgaW4gaXRlcnRvb2xzLmNoYWluKCdBQkMnLCdYWVonKToKCXByaW50KGMpCmZvciBrZXksZ3JvdXAgaW4gaXRlcnRvb2xzLmdyb3VwYnkoJ0FBQUJCQkNDQ0MnKToKCXByaW50KGtleSxsaXN0KGdyb3VwKSkKIyB5b3VyIGNvZGUgZ29lcyBoZXJlCiMgeW91ciBjb2RlIGdvZXMgaGVyZQ==