Use of uninitialized value $_ in scalar chomp at test.pl line 37.
Use of uninitialized value $_ in pattern match (m//) at test.pl line 38.
Use of uninitialized value $_ in numeric gt (>) at test.pl line 39.
Use of uninitialized value $_ in numeric lt (<) at test.pl line 39.

##</code><code>##

        chomp;
        next if /^>/;     # discard headers
        next if length($_) > 30 or length($_) < 15; # discard unwanted sizes