DB<310> @inp = glob '{a,b}'x3


  DB<311> ;m/ ^ (?:(?!\2).)*?  (?{say "<$_ $2>"})  (.) (?=(.|$)) (?!.*\1) /x and say ("found $1 in $_") for @inp
<aaa >
<aab >
<aba >
<aba b>
found b in aba
<abb >
found a in abb
<baa >
found b in baa
<bab >
<bab a>
found a in bab
<bba >
<bbb >


  DB<312>