Could also be:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $dna3 = 'ATCGC';
 my $dna4 = 'AAATTGC';
 ;;
 my $offset = 1;
 substr $dna3, $offset, 0, $dna4;
 print qq{'$dna3'};
"
'AAAATTGCTCGC'
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