#!/usr/bin/perl

$in = "protein_sequences.fasta";
$out = "script.out";

open $INFILE, '<', $in or die "Cannot open '$in': $!";
open $OUTFILE, '>>', $out or die "Cannot open '$out': $!";

while ( $line = <$INFILE> ) {
   print $OUTFILE "$.: $line";
}
close $INFILE;
close $OUTFILE;
