use strict;
use warnings;

my @list = ('foo', 'batz', 'bar');

my $list_ref = \@list;

print $list_ref->[0]."\n";

my %capitals = (
    'Spain' => 'Madrid',
    'France' => 'Paris',
    'Japan' => 'Tokyo',
    );

my $capitals_ref = { 'Spain'=> 'Madrid',
}

$capitals{'Brazil'} = 'Brazilia';

foreach my $k (sort keys %capitals) { 
    print "The capital of $k is $capitals{$k}\n";
}


my $capitals_ref = \%capitals;

print "The hasref is $capitals_ref\n";

print "The capital of Spain is: $capitals_ref->{'Spain'}\n";


foo($capitals_ref);

print "The name is $capitals_ref->{Sweden}\n";

my $x = 2;
print 2+sqrt($x);

sub foo { 
    $_[0]->{Sweden} = 'Stockholm';
}