strs= ['AbcS:sdaf', 'AbcSsdaf']
for s in strs:
splits = s.split(':')
if len(splits) > 1:
print(splits[0])
else:
print(None)
CnN0cnM9IFsnQWJjUzpzZGFmJywgJ0FiY1NzZGFmJ10KZm9yIHMgaW4gc3RyczoKCXNwbGl0cyA9IHMuc3BsaXQoJzonKQoJaWYgbGVuKHNwbGl0cykgPiAxOgoJCXByaW50KHNwbGl0c1swXSkKCWVsc2U6CgkJcHJpbnQoTm9uZSkK