sub my_use {
    my $href = shift;

    for my $key (keys %$href) {
        say $href->{$key};
    }
}

my $href = {
    STRAIGHT_LINE_ID => 1,
    PRORATED_ID      => 2,
    CBP_CUSTOM_ID    => 3
};

my_use($href);
my_use $href;

--output:--
3
2
1
3
2
1