implement a python/typescript method that gets a string of digits. and returns all of the 4 parts permutations which are a valid IPv4.
each number part of an IP can be from 0 to 255, but without a leading 0.
for example "12111" can be (at least)
12.1.1.1 or 1.21.1.1 etc.
ראיון לתפקיד 
