#!/usr/bin/env perl -l

use strict;
use warnings;

my @dna_seqs = qw{ATGCCCGTAC GCTTCCCAGCGC};

print "$_ => ", dna_prot_map($_) for @dna_seqs;

{
    my %code;

    BEGIN {
        %code = qw{ATG M CCC P GTA V GCT A TCC S CAG Q CGC R}
    }

    sub dna_prot_map {
        join '', map $code{substr $_[0], $_*3, 3}, 0..length($_[0])/3-1
    }
}

##</code><code>##

ATGCCCGTAC => MPV
GCTTCCCAGCGC => ASQR

##</code><code>##

sub f {
    state $static_var = ...

    ... do something with $static_var here ...
}

##</code><code>##

{
    my $static_var; BEGIN { $static_var = ... }

    sub f { ... do something with $static_var here ... }
}

##</code><code>##

{
    my $static_var; BEGIN { $static_var = ... }

    sub f { ... do something with $static_var here ... }

    sub g { ... do something with $static_var here ... }
}