DB<13> $str = "I don't think 'don't' isn't >

  DB<14> x split /\b{wb}/, $str
0  'I'
1  ' '
2  'don\'t'
3  ' '
4  'think'
5  ' '
6  '\''
7  'don\'t'
8  '\''
9  ' '
10  'isn\'t'
11  ' '
12  'a'
13  ' '
14  'word'
  DB<15>