my $new_output = '
>YBR018C  GAL7  275433  275933        #this fasta marker line is to be kept
TTTGATATCACTCACAACTATTGCGAAGCGCTTCAGTGAAAAAATCATAA
GGAAAAGTTGTAAATATTATTGGTAGTATTCGTTTGGTAAAGTAGAGGGG
GTAATTTTTCCCCTTTATTTTGTTCATACATTCTTAAATTGCTTTGCCTC
TCCTTTTGGAAAGCTATACTTCGGAGCACTGTTGAGCGAAGGCTCATTAG
ATATATTTTCTGTCATTTTCCTTAACCCAAAAATAAGGGAAAGGGTCCAA
AAAGCGCTCGGACAACTGTTGACCGTGATCCGAAGGACTGGCTATACAGT
GTTCACAAAATAGCCAAGCTGAAAATAATGTGTAGCTATGTTCAGTTAGT
TTGGCTAGCAAAGATATAAAAGCAGGTCGGAAATATTTATGGGCATTATT
ATGCAGAGCATCAACATGATAAAAAAAAACAGTTGAATATTCCCTCAAAA
ATGACTGCTGAAGAATTTGATTTTTCTAGCCATTCCCATAGACGTTACAA
';