sub to_cache {
    my( $ticker, $data ) = @_;

    $data_cache{$ticker} = pack "(A10FFFFL)*", map @$_, @$data;
}

sub from_cache {
    my $ticker = shift;
    return [
        map[
            unpack("A10FFFFL", $_)
        ], unpack '(A[A10FFFFL])*', $data_cache{$ticker}
        ];
}