my @keys = ckeys { $_ }
a => 1,
b => 2,
c => 3,
a => 4,
b => 5,
c => 6;
is_deeply(\@keys, [qw/a b c/]);
my $first_hash = {
a => 1,
b => 2,
c => 3
};
my %second_hash = (
c => 3,
d => 4,
e => 5
);
@keys = ckeys {
uc $_;
} %second_hash, %{$first_hash};
is_deeply(\@keys, [qw/A B C D E/]);
done_testing;