$_= ~/^\w+\s*=\s*\w+\s*\,\?\w+/ ;

Actually, it's worse than that. Because the  = ~ is screwed up (should have been =~), the statement (if that's the statement that's actually in perlynewby's code (if that's actually perlynewby)) is assigning the 1s-complement of the numeric value of the result of the  m// against  $_ to  $_ instead:

c:\@Work\Perl\monks>perl -wMstrict -le
"$_ = 'x=x,?x';
 print qq{'$_'};
 ;;
 $_= ~/^\w+\s*=\s*\w+\s*\,\?\w+/ ;
 print qq{'$_'};
 ;;
 $_ = '----';
 print qq{'$_'};
 ;;
 $_= ~/^\w+\s*=\s*\w+\s*\,\?\w+/ ;
 print qq{'$_'};
"
'x=x,?x'
'4294967294'
'----'
'4294967295'
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