push (@fasta, $seq);
push @fasta, "> COULDN'T FIND IT" unless defined $seq;

##</code><code>##

if (defined $seq) { push @fasta, $seq }
else { push @fasta, "> COULDN'T FIND IT" }

##</code><code>##

defined $seq ? push @fasta, $seq : push @fasta, "> COULDN'T FIND IT" ;