sub inc{
   my $ref=shift;
   my $span=shift;
   $span?($span--):($span=1);

   my @b=map{ clone([@$ref[$_-$span..$_]])  }($span..$#$ref);

   \@b
}
sub clone{#clone references
   my $ref=shift;
   my@array=map{ ref($_)?clone($_):$_ }@$ref;
   \@array
}
my@b=(1..5);
my $c = inc(inc(\@b));
print Dumper $c;

##</code><code>##

$VAR1 = [
          [
            [
              1,
              2
            ],
            [
              2,
              3
            ]
          ],
          [
            [
              2,
              3
            ],
            [
              3,
              4
            ]
          ],
          [
            [
              3,
              4
            ],
            [
              4,
              5
            ]
          ]
        ];

##</code><code>##

@a = (1,2,3,4,5,6);
increment(\@a);

#produces tuples of:
[1,2],[2,3],[3,4],[4,5],[5,6] #yay!!

##</code><code>##

$VAR1 = [
          [
            [
              1,
              2
            ],
            [
              2,
              3
            ]
          ],
          [
            $VAR1->[0][1],
            [
              3,
              4
            ]
          ],
          [
            $VAR1->[1][1],
            [
              4,
              6
            ]
          ]
        ];

##</code><code>##

my @a = (1,2,3,4,6);

print Dumper increment(increment(\@a));

sub increment{
   my $d=shift;
   my @b;
   for my $i (1..$#$d){
      my @a = @$d[$i-1..$i];
      push @b,\@a;
   }
   \@b
}