Consider the string `"1 2 36 4 8"`. Lets take pairs of these numbers, concatenate each pair and determine how many of them of divisible by `k`. 
```Pearl 
If k = 3, we get following numbers ['12', '18', '21', '24', '42', '48', '81', '84'], all divisible by 3.   
Note:
-- 21 and 12 are different pairs. 
-- Elements must be from different indices, so '3636` is not a valid. 
```
Given a string of numbers and an integer `k`, return the number of pairs that when concatenated, are divisible by `k`.
```
solve("1 2 36 4 8", 3) = 8, because they are ['12', '18', '21', '24', '42', '48', '81', '84']
solve("1 3 6 3", 3) = 6. They are ['36', '33', '63', '63', '33', '36']
```
More examples in test cases. Good luck!
Please also try [Simple remove duplicates](https://www.codewars.com/kata/5ba38ba180824a86850000f7)
from itertools import permutations, filterfalse

def solve(s, k):
    return len(list(filterfalse(lambda x: int(''.join(x))%k, permutations(s.split(), 2))))
from itertools import permutations, filterfalse

def solve(s, k):
    return len(list(filterfalse(lambda x: int(''.join(x))%k, permutations(s.split(), 2))))