c:\@Work\Perl\monks>perl

use strict;
use warnings;

$\ = $/;

my @ra = 'a' .. 'g';

print @ra[    0 .. 2    ];  # python a[:3] = 'abc' (ie. select first 3)
print @ra[ -@ra .. -4   ];  # python a[:-3] = 'abcd' (ie. omit last 3)
print @ra[    3 .. $#ra ];  # python a[3:] = 'defg' (ie. omit first 3)
print @ra[   -3 .. -1   ];  # python a[-3:] = 'efg' (ie. select last 3)

^Z
abc
abcd
defg
efg