I feel we need more test case.

1. easy multiple spaces case. Currently edge test9/9 is the first multiple space case. But it is not easy to find such bug.

   checkio('a  b', 'a b')
   

2. multiple keyword in same word case.

   checkio('aaa', 'a')
   

Another request, I want you to also allows this as an answer like below.

checkio('ab', 'a b') = <snap>a</snap><snap>b</snap> or <snap>ab</snap>