How do I slice a string every 3 indices? [duplicate]

Answer 1

In short, you can't.

In longer, you'll need to write your own function, possibly:

def split(str, num):
    return [ str[start:start+num] for start in range(0, len(str), num) ]

For example:

>>> split("xxxXXX", 3)
['xxx', 'XXX']
>>> split("xxxXXXxx", 3)
['xxx', 'XXX', 'xx']