$ wget ftp://ftp.ncbi.nih.gov/genomes/Homo_sapiens/CHR_20/hs_ref_GRCh38.p12_chr20.fa.gz
--2019-01-23 07:54:51--  ftp://ftp.ncbi.nih.gov/genomes/Homo_sapiens/CHR_20/hs_ref_GRCh38.p12_chr20.fa.gz
           => ‘hs_ref_GRCh38.p12_chr20.fa.gz’
Resolving ftp.ncbi.nih.gov (ftp.ncbi.nih.gov)... 130.14.250.12, 2607:f220:41e:250::12
Connecting to ftp.ncbi.nih.gov (ftp.ncbi.nih.gov)|130.14.250.12|:21... failed: Connection timed out.
Connecting to ftp.ncbi.nih.gov (ftp.ncbi.nih.gov)|2607:f220:41e:250::12|:21... failed: Network is unreachable.
$ 

##</code><code>##

$ mkdir Markov
$ cd Markov/
$ touch Ndimensional.pm
$ gedit Ndimensional.pm &
[1] 20524
$ pwd
/home/bob/2.scripts/pages/7.cw/template_stuff/crosswords/eugene/Markov
[1]+  Done                    gedit Ndimensional.pm
^^^^ pasted in source
$ cd ..
$ ls
1.bliako.pl  bliako1.pm  Markov
$ ./1.bliako.pl 
Can't locate Markov/Ndimensional.pm in @INC (you may need to install the Markov::Ndimensional module) (@INC contains: Markov /home/bob/perl5/lib/perl5/x86_64-linux-gnu-thread-multi /home/bob/perl5/lib/perl5 /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.26.1 /usr/local/share/perl/5.26.1 /usr/lib/x86_64-linux-gnu/perl5/5.26 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.26 /usr/share/perl/5.26 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base) at ./1.bliako.pl line 13.
BEGIN failed--compilation aborted at ./1.bliako.pl line 13.
$ 

##</code><code>##

$ cat 1.bliako.pl 
#!/usr/bin/env perl

# FILE: analyse_DNA_sequence.pl
# by bliako

use strict;
use warnings;

use Getopt::Long;
use Data::Dump qw/dump/;
use lib 'Markov';

use Markov::Ndimensional;